From 38902d9a642be8dd3876d42db8ef9a90b33e45b9 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 18 Dec 2021 16:05:30 +0100
Subject: [PATCH 1/4] 2021: d18: ex1: add input

---
 2021/d18/ex1/input | 100 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 2021/d18/ex1/input

diff --git a/2021/d18/ex1/input b/2021/d18/ex1/input
new file mode 100644
index 0000000..1dd0bc9
--- /dev/null
+++ b/2021/d18/ex1/input
@@ -0,0 +1,100 @@
+[[3,[8,[2,1]]],[[[0,6],[0,2]],3]]
+[[[1,[8,5]],[[3,9],0]],2]
+[5,[[5,[3,8]],[7,4]]]
+[1,[[[0,4],[8,5]],6]]
+[[[1,[0,3]],2],[2,[0,[7,9]]]]
+[[[4,[4,4]],[[7,2],[7,1]]],9]
+[5,[4,4]]
+[[0,[[2,6],[8,9]]],[[4,5],2]]
+[[[8,2],0],3]
+[[9,0],[3,3]]
+[[[[5,2],2],5],5]
+[[[1,6],[[0,4],[7,7]]],[[1,4],[[6,5],5]]]
+[[[[4,1],[4,1]],[2,[5,5]]],[1,[0,[0,6]]]]
+[[[[1,5],1],[8,4]],[9,[3,4]]]
+[[1,[3,3]],[[[7,4],[8,1]],2]]
+[3,[[[2,1],4],[5,4]]]
+[6,[[0,[1,9]],[[4,0],8]]]
+[5,[7,[7,[8,8]]]]
+[[[[6,2],[5,8]],[5,[3,1]]],[[7,9],[[2,0],6]]]
+[[[7,[7,9]],[5,7]],[[[9,3],[6,9]],[[1,2],[2,3]]]]
+[[[[4,1],2],[1,[6,6]]],[[[2,2],[8,8]],4]]
+[[[[3,7],4],8],[6,[[0,2],3]]]
+[[[[1,8],2],3],[[9,[1,7]],[[0,0],[6,8]]]]
+[[[9,[5,2]],7],[[8,6],[8,[1,2]]]]
+[[[7,[1,0]],[[6,0],[8,4]]],[[[7,8],5],[3,[1,2]]]]
+[[[[2,5],9],[[8,2],0]],0]
+[0,[[[7,5],[4,1]],[5,[6,6]]]]
+[[[[3,6],2],[[1,1],[6,6]]],0]
+[[[[0,9],[2,5]],[2,[3,2]]],[6,3]]
+[3,[[9,[1,4]],[[0,8],[4,6]]]]
+[1,[[5,[5,9]],[9,0]]]
+[[[6,8],4],[[[6,6],2],[[3,9],2]]]
+[5,[[[7,5],[4,8]],0]]
+[[9,[6,6]],[9,[[6,8],[6,4]]]]
+[[[4,8],[0,[2,8]]],[7,[[4,5],[1,6]]]]
+[[[6,[8,6]],2],[[[2,9],[2,4]],[0,2]]]
+[[[0,[5,6]],[[3,8],3]],[[3,1],7]]
+[[1,[8,1]],[1,[6,[7,1]]]]
+[[[5,[9,6]],[3,5]],2]
+[[3,7],[[[2,5],[4,1]],[3,[5,6]]]]
+[[8,7],[[9,6],3]]
+[[[[4,2],[4,8]],[7,[4,5]]],2]
+[[[[6,7],6],3],[[[6,7],4],0]]
+[[[0,1],[[9,1],[2,9]]],9]
+[[[[8,5],[5,8]],[0,7]],[0,[8,[3,2]]]]
+[[4,[[6,5],[1,9]]],[[[0,0],1],6]]
+[[[[9,5],9],[2,[6,3]]],[[2,9],[6,9]]]
+[[[7,[5,0]],1],[7,[[8,7],3]]]
+[[[2,4],2],[[[3,0],6],[[0,2],[9,2]]]]
+[[1,[[7,3],[4,3]]],[[[3,9],[1,1]],[3,6]]]
+[[[[4,7],7],[[7,1],[2,3]]],[1,[[7,6],[5,6]]]]
+[[0,[5,2]],0]
+[[[[6,6],[4,8]],8],[[0,[7,4]],8]]
+[[4,[7,2]],[[[0,8],1],[9,5]]]
+[0,0]
+[[[[3,7],6],3],[3,[[3,3],1]]]
+[[[6,5],7],[[3,5],[[6,4],[4,9]]]]
+[[4,[[7,9],9]],9]
+[5,[8,[[7,4],1]]]
+[[[[2,4],[5,7]],8],[[[7,6],[6,9]],[[3,9],[6,4]]]]
+[[[4,8],3],[[[3,9],7],0]]
+[0,[8,[[4,2],3]]]
+[[[[0,1],[5,8]],[7,2]],[2,4]]
+[[6,[8,[1,9]]],[[[6,5],[8,1]],[7,[6,4]]]]
+[[9,3],[5,[0,6]]]
+[[2,[7,[2,0]]],[[2,1],[5,5]]]
+[[[0,[7,0]],[[0,4],[4,9]]],[8,[[6,1],[6,3]]]]
+[[[[5,7],[3,2]],[0,[5,0]]],[[0,[1,6]],3]]
+[[[[6,3],[9,5]],[9,9]],[[5,[8,3]],[[0,0],[0,3]]]]
+[[6,[4,9]],[[[9,9],[8,4]],4]]
+[0,[2,5]]
+[[[[7,9],[1,2]],[3,3]],[[[7,2],7],[[1,6],0]]]
+[[[[8,0],2],8],[[[1,5],9],9]]
+[[[0,[6,9]],4],[[[4,8],5],4]]
+[[6,[[0,3],4]],[0,[[8,3],1]]]
+[[[1,2],[2,[3,3]]],[6,7]]
+[[0,[[7,4],5]],[3,[[8,2],0]]]
+[[[[0,1],[1,7]],[[2,7],[5,9]]],[[[7,0],0],[8,1]]]
+[[6,4],[3,0]]
+[[[[6,6],4],[5,1]],[7,3]]
+[[[[9,2],3],[8,[4,8]]],7]
+[[5,[[2,2],[9,2]]],[[[1,8],0],[8,[6,3]]]]
+[2,[[0,0],[0,[9,9]]]]
+[[4,4],[[6,5],[6,5]]]
+[[[[9,1],2],4],5]
+[[[[2,1],[3,1]],[[2,6],9]],5]
+[[[9,[0,6]],7],[[8,3],[[8,1],2]]]
+[[[6,[0,0]],[2,[0,0]]],[[[0,4],8],3]]
+[[[[4,1],[2,9]],[6,5]],3]
+[[9,[[9,4],8]],[[[5,5],3],[[3,4],4]]]
+[8,[9,[[0,3],1]]]
+[9,[[[6,0],4],9]]
+[[6,[2,9]],[[[2,7],[5,3]],0]]
+[[[4,1],5],[8,[[0,7],4]]]
+[[[[2,5],5],[[8,2],[8,9]]],[[9,6],[[0,3],[2,3]]]]
+[6,1]
+[[1,7],4]
+[[8,7],0]
+[[[[5,4],7],5],[[[6,1],5],[5,[5,5]]]]
+[[[6,[1,5]],[0,[7,0]]],[[[1,5],3],[5,[1,0]]]]

From 2be3cf43275408bbcdf7850f48f7ce1cdc5b7921 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 18 Dec 2021 16:05:38 +0100
Subject: [PATCH 2/4] 2021: d18: ex1: add solution

---
 2021/d18/ex1/ex1.py | 208 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 208 insertions(+)
 create mode 100755 2021/d18/ex1/ex1.py

diff --git a/2021/d18/ex1/ex1.py b/2021/d18/ex1/ex1.py
new file mode 100755
index 0000000..7a02746
--- /dev/null
+++ b/2021/d18/ex1/ex1.py
@@ -0,0 +1,208 @@
+#!/usr/bin/env python
+
+import functools
+import itertools
+import sys
+from dataclasses import dataclass
+from typing import Iterator, List, Optional, Tuple
+
+
+@dataclass
+class Tree:
+    parent: Optional["Pair"]
+
+
+@dataclass
+class Pair(Tree):
+    left: Tree
+    right: Tree
+
+
+@dataclass
+class Num(Tree):
+    val: int
+
+
+# True means left, False means right
+Path = List[bool]
+
+
+def solve(input: List[str]) -> int:
+    def make_pair(left: Tree, right: Tree, parent: Optional[Pair] = None) -> Pair:
+        pair = Pair(parent=parent, left=left, right=right)
+        pair.left.parent = pair
+        pair.right.parent = pair
+        return pair
+
+    def make_num(val: int, parent: Optional[Pair] = None) -> Num:
+        return Num(parent=parent, val=val)
+
+    # FIXME: remove this
+    def debug(tree: Tree) -> str:
+        if isinstance(tree, Pair):
+            return f"[{debug(tree.left)},{debug(tree.right)}]"
+        assert isinstance(tree, Num)
+        return str(tree.val)
+
+    def parse() -> List[Tree]:
+        def parse_snailfish_number(line: str) -> Tree:
+            def parse_index(input: str, index: int = 0) -> Tuple[int, Tree]:
+                if input[index] == "[":
+                    left_index, left = parse_index(input, index + 1)
+                    assert input[left_index] == ","  # Sanity check
+                    right_index, right = parse_index(input, left_index + 1)
+                    assert input[right_index] == "]"  # Sanity check
+                    return right_index + 1, make_pair(left, right)
+                res = 0
+                for i in itertools.count(index):
+                    if i < len(input) and input[i] in set(str(i) for i in range(10)):
+                        res = res * 10 + int(input[i])
+                    else:
+                        return i, make_num(res)
+                assert False  # Sanity check
+
+            __, res = parse_index(line)
+            return res
+
+        return [parse_snailfish_number(line) for line in input]
+
+    def explosion_path(number: Tree) -> Optional[Path]:
+        def dfs(number: Pair, path: Path = []) -> Optional[Path]:
+            if (
+                len(path) >= 4
+                and isinstance(number.left, Num)
+                and isinstance(number.right, Num)
+            ):
+                return path
+            if isinstance(number.left, Pair):
+                left_path = dfs(number.left, path + [True])
+                if left_path is not None:
+                    return left_path
+            if isinstance(number.right, Pair):
+                right_path = dfs(number.right, path + [False])
+                if right_path is not None:
+                    return right_path
+            return None
+
+        assert isinstance(number, Pair)  # Sanity check
+        return dfs(number)
+
+    def split_path(number: Tree) -> Optional[Path]:
+        def dfs(number: Pair, path: Path = []) -> Optional[Path]:
+            if isinstance(number.left, Num):
+                if number.left.val >= 10:
+                    return path + [True]
+            else:
+                assert isinstance(number.left, Pair)  # Sanity check
+                if (left_path := dfs(number.left, path + [True])) is not None:
+                    return left_path
+            if isinstance(number.right, Num):
+                if number.right.val >= 10:
+                    return path + [False]
+            else:
+                assert isinstance(number.right, Pair)  # Sanity check
+                if (right_path := dfs(number.right, path + [False])) is not None:
+                    return right_path
+            return None
+
+        assert isinstance(number, Pair)  # Sanity check
+        return dfs(number)
+
+    def explode(number: Tree, path: Path) -> Tree:
+        def walk(number: Tree, reverse: bool) -> Iterator[Tree]:
+            if isinstance(number, Num):
+                yield number
+            else:
+                assert isinstance(number, Pair)  # Sanity check
+                first, second = (
+                    (number.right, number.left)
+                    if reverse
+                    else (number.left, number.right)
+                )
+                yield from walk(first, reverse)
+                yield number
+                yield from walk(second, reverse)
+
+        def next_num(number: Tree, reverse: bool) -> Optional[Num]:
+            if number.parent is None:
+                return None
+            sibling = number.parent.left if reverse else number.parent.right
+            if number is sibling:
+                return next_num(number.parent, reverse)
+            for node in walk(sibling, reverse=reverse):
+                if isinstance(node, Num):
+                    return node
+            return None
+
+        assert isinstance(number, Pair)  # Sanity check
+
+        if len(path) == 0:
+            p, n = next_num(number, reverse=True), next_num(number, reverse=False)
+            if p is not None:
+                assert isinstance(number.left, Num)  # Safety check
+                p.val += number.left.val
+            if n is not None:
+                assert isinstance(number.right, Num)  # Safety check
+                n.val += number.right.val
+            return make_num(0)
+
+        parent, left, right = number.parent, number.left, number.right
+        if path[0]:
+            left = explode(number.left, path[1:])
+        else:
+            right = explode(number.right, path[1:])
+
+        return make_pair(parent=parent, left=left, right=right)
+
+    def split(number: Tree, path: Path) -> Tree:
+        def split_int(num: int, parent: Optional[Pair]) -> Tree:
+            assert num >= 0  # Sanity check
+            left = num // 2
+            right = num - left
+            res = make_pair(left=make_num(left), right=make_num(right), parent=parent)
+            return res
+
+        if len(path) == 0:
+            assert isinstance(number, Num)  # Sanity check
+            return split_int(number.val, number.parent)
+
+        assert isinstance(number, Pair)  # Sanity check
+
+        parent, left, right = number.parent, number.left, number.right
+        if path[0]:
+            left = split(number.left, path[1:])
+        else:
+            right = split(number.right, path[1:])
+
+        return make_pair(parent=parent, left=left, right=right)
+
+    def reduce(number: Tree) -> Tree:
+        path = explosion_path(number)
+        if path is not None:
+            return reduce(explode(number, path))
+        path = split_path(number)
+        if path is not None:
+            return reduce(split(number, path))
+        return number
+
+    def add(left: Tree, right: Tree) -> Tree:
+        return reduce(make_pair(left=left, right=right))
+
+    def magnitude(number: Tree) -> int:
+        if isinstance(number, Num):
+            return number.val
+        assert isinstance(number, Pair)  # Safety check
+        return 3 * magnitude(number.left) + 2 * magnitude(number.right)
+
+    numbers = parse()
+    result = functools.reduce(add, numbers)
+    return magnitude(result)
+
+
+def main() -> None:
+    input = [line.strip() for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()

From c0bf6fe213cc23294f877b4327c6344884bc40fb Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 18 Dec 2021 16:05:48 +0100
Subject: [PATCH 3/4] 2021: d18: ex2: add input

---
 2021/d18/ex2/input | 100 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 2021/d18/ex2/input

diff --git a/2021/d18/ex2/input b/2021/d18/ex2/input
new file mode 100644
index 0000000..1dd0bc9
--- /dev/null
+++ b/2021/d18/ex2/input
@@ -0,0 +1,100 @@
+[[3,[8,[2,1]]],[[[0,6],[0,2]],3]]
+[[[1,[8,5]],[[3,9],0]],2]
+[5,[[5,[3,8]],[7,4]]]
+[1,[[[0,4],[8,5]],6]]
+[[[1,[0,3]],2],[2,[0,[7,9]]]]
+[[[4,[4,4]],[[7,2],[7,1]]],9]
+[5,[4,4]]
+[[0,[[2,6],[8,9]]],[[4,5],2]]
+[[[8,2],0],3]
+[[9,0],[3,3]]
+[[[[5,2],2],5],5]
+[[[1,6],[[0,4],[7,7]]],[[1,4],[[6,5],5]]]
+[[[[4,1],[4,1]],[2,[5,5]]],[1,[0,[0,6]]]]
+[[[[1,5],1],[8,4]],[9,[3,4]]]
+[[1,[3,3]],[[[7,4],[8,1]],2]]
+[3,[[[2,1],4],[5,4]]]
+[6,[[0,[1,9]],[[4,0],8]]]
+[5,[7,[7,[8,8]]]]
+[[[[6,2],[5,8]],[5,[3,1]]],[[7,9],[[2,0],6]]]
+[[[7,[7,9]],[5,7]],[[[9,3],[6,9]],[[1,2],[2,3]]]]
+[[[[4,1],2],[1,[6,6]]],[[[2,2],[8,8]],4]]
+[[[[3,7],4],8],[6,[[0,2],3]]]
+[[[[1,8],2],3],[[9,[1,7]],[[0,0],[6,8]]]]
+[[[9,[5,2]],7],[[8,6],[8,[1,2]]]]
+[[[7,[1,0]],[[6,0],[8,4]]],[[[7,8],5],[3,[1,2]]]]
+[[[[2,5],9],[[8,2],0]],0]
+[0,[[[7,5],[4,1]],[5,[6,6]]]]
+[[[[3,6],2],[[1,1],[6,6]]],0]
+[[[[0,9],[2,5]],[2,[3,2]]],[6,3]]
+[3,[[9,[1,4]],[[0,8],[4,6]]]]
+[1,[[5,[5,9]],[9,0]]]
+[[[6,8],4],[[[6,6],2],[[3,9],2]]]
+[5,[[[7,5],[4,8]],0]]
+[[9,[6,6]],[9,[[6,8],[6,4]]]]
+[[[4,8],[0,[2,8]]],[7,[[4,5],[1,6]]]]
+[[[6,[8,6]],2],[[[2,9],[2,4]],[0,2]]]
+[[[0,[5,6]],[[3,8],3]],[[3,1],7]]
+[[1,[8,1]],[1,[6,[7,1]]]]
+[[[5,[9,6]],[3,5]],2]
+[[3,7],[[[2,5],[4,1]],[3,[5,6]]]]
+[[8,7],[[9,6],3]]
+[[[[4,2],[4,8]],[7,[4,5]]],2]
+[[[[6,7],6],3],[[[6,7],4],0]]
+[[[0,1],[[9,1],[2,9]]],9]
+[[[[8,5],[5,8]],[0,7]],[0,[8,[3,2]]]]
+[[4,[[6,5],[1,9]]],[[[0,0],1],6]]
+[[[[9,5],9],[2,[6,3]]],[[2,9],[6,9]]]
+[[[7,[5,0]],1],[7,[[8,7],3]]]
+[[[2,4],2],[[[3,0],6],[[0,2],[9,2]]]]
+[[1,[[7,3],[4,3]]],[[[3,9],[1,1]],[3,6]]]
+[[[[4,7],7],[[7,1],[2,3]]],[1,[[7,6],[5,6]]]]
+[[0,[5,2]],0]
+[[[[6,6],[4,8]],8],[[0,[7,4]],8]]
+[[4,[7,2]],[[[0,8],1],[9,5]]]
+[0,0]
+[[[[3,7],6],3],[3,[[3,3],1]]]
+[[[6,5],7],[[3,5],[[6,4],[4,9]]]]
+[[4,[[7,9],9]],9]
+[5,[8,[[7,4],1]]]
+[[[[2,4],[5,7]],8],[[[7,6],[6,9]],[[3,9],[6,4]]]]
+[[[4,8],3],[[[3,9],7],0]]
+[0,[8,[[4,2],3]]]
+[[[[0,1],[5,8]],[7,2]],[2,4]]
+[[6,[8,[1,9]]],[[[6,5],[8,1]],[7,[6,4]]]]
+[[9,3],[5,[0,6]]]
+[[2,[7,[2,0]]],[[2,1],[5,5]]]
+[[[0,[7,0]],[[0,4],[4,9]]],[8,[[6,1],[6,3]]]]
+[[[[5,7],[3,2]],[0,[5,0]]],[[0,[1,6]],3]]
+[[[[6,3],[9,5]],[9,9]],[[5,[8,3]],[[0,0],[0,3]]]]
+[[6,[4,9]],[[[9,9],[8,4]],4]]
+[0,[2,5]]
+[[[[7,9],[1,2]],[3,3]],[[[7,2],7],[[1,6],0]]]
+[[[[8,0],2],8],[[[1,5],9],9]]
+[[[0,[6,9]],4],[[[4,8],5],4]]
+[[6,[[0,3],4]],[0,[[8,3],1]]]
+[[[1,2],[2,[3,3]]],[6,7]]
+[[0,[[7,4],5]],[3,[[8,2],0]]]
+[[[[0,1],[1,7]],[[2,7],[5,9]]],[[[7,0],0],[8,1]]]
+[[6,4],[3,0]]
+[[[[6,6],4],[5,1]],[7,3]]
+[[[[9,2],3],[8,[4,8]]],7]
+[[5,[[2,2],[9,2]]],[[[1,8],0],[8,[6,3]]]]
+[2,[[0,0],[0,[9,9]]]]
+[[4,4],[[6,5],[6,5]]]
+[[[[9,1],2],4],5]
+[[[[2,1],[3,1]],[[2,6],9]],5]
+[[[9,[0,6]],7],[[8,3],[[8,1],2]]]
+[[[6,[0,0]],[2,[0,0]]],[[[0,4],8],3]]
+[[[[4,1],[2,9]],[6,5]],3]
+[[9,[[9,4],8]],[[[5,5],3],[[3,4],4]]]
+[8,[9,[[0,3],1]]]
+[9,[[[6,0],4],9]]
+[[6,[2,9]],[[[2,7],[5,3]],0]]
+[[[4,1],5],[8,[[0,7],4]]]
+[[[[2,5],5],[[8,2],[8,9]]],[[9,6],[[0,3],[2,3]]]]
+[6,1]
+[[1,7],4]
+[[8,7],0]
+[[[[5,4],7],5],[[[6,1],5],[5,[5,5]]]]
+[[[6,[1,5]],[0,[7,0]]],[[[1,5],3],[5,[1,0]]]]

From 8bf78654a5ab20e0ba70ffe0de29abd866249c2e Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 18 Dec 2021 16:05:53 +0100
Subject: [PATCH 4/4] 2021: d18: ex2: add solution

---
 2021/d18/ex2/ex2.py | 211 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 211 insertions(+)
 create mode 100755 2021/d18/ex2/ex2.py

diff --git a/2021/d18/ex2/ex2.py b/2021/d18/ex2/ex2.py
new file mode 100755
index 0000000..56c8d48
--- /dev/null
+++ b/2021/d18/ex2/ex2.py
@@ -0,0 +1,211 @@
+#!/usr/bin/env python
+
+import functools
+import itertools
+import sys
+from copy import deepcopy
+from dataclasses import dataclass
+from typing import Iterator, List, Optional, Tuple
+
+
+@dataclass
+class Tree:
+    parent: Optional["Pair"]
+
+
+@dataclass
+class Pair(Tree):
+    left: Tree
+    right: Tree
+
+
+@dataclass
+class Num(Tree):
+    val: int
+
+
+# True means left, False means right
+Path = List[bool]
+
+
+def solve(input: List[str]) -> int:
+    def make_pair(left: Tree, right: Tree, parent: Optional[Pair] = None) -> Pair:
+        pair = Pair(parent=parent, left=left, right=right)
+        pair.left.parent = pair
+        pair.right.parent = pair
+        return pair
+
+    def make_num(val: int, parent: Optional[Pair] = None) -> Num:
+        return Num(parent=parent, val=val)
+
+    # FIXME: remove this
+    def debug(tree: Tree) -> str:
+        if isinstance(tree, Pair):
+            return f"[{debug(tree.left)},{debug(tree.right)}]"
+        assert isinstance(tree, Num)
+        return str(tree.val)
+
+    def parse() -> List[Tree]:
+        def parse_snailfish_number(line: str) -> Tree:
+            def parse_index(input: str, index: int = 0) -> Tuple[int, Tree]:
+                if input[index] == "[":
+                    left_index, left = parse_index(input, index + 1)
+                    assert input[left_index] == ","  # Sanity check
+                    right_index, right = parse_index(input, left_index + 1)
+                    assert input[right_index] == "]"  # Sanity check
+                    return right_index + 1, make_pair(left, right)
+                res = 0
+                for i in itertools.count(index):
+                    if i < len(input) and input[i] in set(str(i) for i in range(10)):
+                        res = res * 10 + int(input[i])
+                    else:
+                        return i, make_num(res)
+                assert False  # Sanity check
+
+            __, res = parse_index(line)
+            return res
+
+        return [parse_snailfish_number(line) for line in input]
+
+    def explosion_path(number: Tree) -> Optional[Path]:
+        def dfs(number: Pair, path: Path = []) -> Optional[Path]:
+            if (
+                len(path) >= 4
+                and isinstance(number.left, Num)
+                and isinstance(number.right, Num)
+            ):
+                return path
+            if isinstance(number.left, Pair):
+                left_path = dfs(number.left, path + [True])
+                if left_path is not None:
+                    return left_path
+            if isinstance(number.right, Pair):
+                right_path = dfs(number.right, path + [False])
+                if right_path is not None:
+                    return right_path
+            return None
+
+        assert isinstance(number, Pair)  # Sanity check
+        return dfs(number)
+
+    def split_path(number: Tree) -> Optional[Path]:
+        def dfs(number: Pair, path: Path = []) -> Optional[Path]:
+            if isinstance(number.left, Num):
+                if number.left.val >= 10:
+                    return path + [True]
+            else:
+                assert isinstance(number.left, Pair)  # Sanity check
+                if (left_path := dfs(number.left, path + [True])) is not None:
+                    return left_path
+            if isinstance(number.right, Num):
+                if number.right.val >= 10:
+                    return path + [False]
+            else:
+                assert isinstance(number.right, Pair)  # Sanity check
+                if (right_path := dfs(number.right, path + [False])) is not None:
+                    return right_path
+            return None
+
+        assert isinstance(number, Pair)  # Sanity check
+        return dfs(number)
+
+    def explode(number: Tree, path: Path) -> Tree:
+        def walk(number: Tree, reverse: bool) -> Iterator[Tree]:
+            if isinstance(number, Num):
+                yield number
+            else:
+                assert isinstance(number, Pair)  # Sanity check
+                first, second = (
+                    (number.right, number.left)
+                    if reverse
+                    else (number.left, number.right)
+                )
+                yield from walk(first, reverse)
+                yield number
+                yield from walk(second, reverse)
+
+        def next_num(number: Tree, reverse: bool) -> Optional[Num]:
+            if number.parent is None:
+                return None
+            sibling = number.parent.left if reverse else number.parent.right
+            if number is sibling:
+                return next_num(number.parent, reverse)
+            for node in walk(sibling, reverse=reverse):
+                if isinstance(node, Num):
+                    return node
+            return None
+
+        assert isinstance(number, Pair)  # Sanity check
+
+        if len(path) == 0:
+            p, n = next_num(number, reverse=True), next_num(number, reverse=False)
+            if p is not None:
+                assert isinstance(number.left, Num)  # Safety check
+                p.val += number.left.val
+            if n is not None:
+                assert isinstance(number.right, Num)  # Safety check
+                n.val += number.right.val
+            return make_num(0)
+
+        parent, left, right = number.parent, number.left, number.right
+        if path[0]:
+            left = explode(number.left, path[1:])
+        else:
+            right = explode(number.right, path[1:])
+
+        return make_pair(parent=parent, left=left, right=right)
+
+    def split(number: Tree, path: Path) -> Tree:
+        def split_int(num: int, parent: Optional[Pair]) -> Tree:
+            assert num >= 0  # Sanity check
+            left = num // 2
+            right = num - left
+            res = make_pair(left=make_num(left), right=make_num(right), parent=parent)
+            return res
+
+        if len(path) == 0:
+            assert isinstance(number, Num)  # Sanity check
+            return split_int(number.val, number.parent)
+
+        assert isinstance(number, Pair)  # Sanity check
+
+        parent, left, right = number.parent, number.left, number.right
+        if path[0]:
+            left = split(number.left, path[1:])
+        else:
+            right = split(number.right, path[1:])
+
+        return make_pair(parent=parent, left=left, right=right)
+
+    def reduce(number: Tree) -> Tree:
+        path = explosion_path(number)
+        if path is not None:
+            return reduce(explode(number, path))
+        path = split_path(number)
+        if path is not None:
+            return reduce(split(number, path))
+        return number
+
+    def add(left: Tree, right: Tree) -> Tree:
+        return reduce(make_pair(left=left, right=right))
+
+    def magnitude(number: Tree) -> int:
+        if isinstance(number, Num):
+            return number.val
+        assert isinstance(number, Pair)  # Safety check
+        return 3 * magnitude(number.left) + 2 * magnitude(number.right)
+
+    numbers = parse()
+    return max(
+        magnitude(add(deepcopy(l), deepcopy(r)))
+        for l, r in itertools.permutations(numbers, 2)
+    )
+
+
+def main() -> None:
+    input = [line.strip() for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()