class Solution:
    def climbStairs(self, n: int) -> int:
        if n == 0:
            return 1
        if n < 0:
            return 0
        return self.climbStairs(n - 1) + self.climbStairs(n - 2)


if __name__ == "__main__":
    s = Solution()
    print(s.climbStairs(5))
    print(s.climbStairs(30))
    print(s.climbStairs(1))