def is_ipv4_address(input_string: str) -> bool:
    parts = input_string.split(".")
    if len(parts) != 4:
        return False

    for v in parts:
        try:
            n = int(v)
        except ValueError:
            return False
        if n > 255 or v == "" or v != str(n):
            return False

    return True