diff --git a/2022/d04/ex1/ex1.py b/2022/d04/ex1/ex1.py
new file mode 100755
index 0000000..8ec60f6
--- /dev/null
+++ b/2022/d04/ex1/ex1.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+import sys
+
+
+def solve(input: list[str]) -> int:
+    def is_redundant(line: str) -> bool:
+        def assignment_to_set(elf: str) -> set[int]:
+            start, end = elf.split("-")
+            return set(range(int(start), int(end) + 1))
+
+        elf1, elf2 = map(assignment_to_set, line.split(","))
+        return elf1.issubset(elf2) or elf2.issubset(elf1)
+
+    return sum(map(is_redundant, input))
+
+
+def main() -> None:
+    input = sys.stdin.read().splitlines()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()