Do till day 5.

d4.py

@@ -0,0 +1,64 @@
+import re
+from string import ascii_lowercase, ascii_uppercase
+
+EXAMPLE = """
+2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8
+"""
+
+def clean(text: str) -> list[str]:
+    return list(filter(lambda l: l.strip() != "", text.splitlines()))
+
+def solve(lines: list[str]):
+    s = 0
+    for (i, line) in enumerate(lines):
+        s1, s2 = line.split(',')
+        a, b = s1.split('-')
+        c, d = s2.split('-')
+        a = int(a)
+        b = int(b)
+        c = int(c)
+        d = int(d)
+        a = set(list(range(a, b + 1)))
+        b = set(list(range(c, d + 1)))
+        if a <= b or b <= a:
+            s += 1
+    return s
+
+def solve2(lines: list[str]):
+    s = 0
+    for (i, line) in enumerate(lines):
+        s1, s2 = line.split(',')
+        a, b = s1.split('-')
+        c, d = s2.split('-')
+        a = int(a)
+        b = int(b)
+        c = int(c)
+        d = int(d)
+        a = set(list(range(a, b + 1)))
+        b = set(list(range(c, d + 1)))
+        c = a.intersection(b)
+        if c:
+            s += 1
+    # 7:08
+    return s
+
+def main():
+    example = clean(EXAMPLE)
+    print("Example  1:", solve(example))
+
+    data = clean(open("i4.txt").read())
+    print("Solution 1:", solve(data))
+
+    example = clean(EXAMPLE)
+    print("Example  2:", solve2(example))
+
+    data = clean(open("i4.txt").read())
+    print("Solution 2:", solve2(data))
+
+if __name__ == "__main__":
+    main()