class Solution:
    def climbStairs(self, n: int) -> int:
       #tabulation
        if n<=2:
            return n
        
        dp=[0]*(n+1)
        dp[1]=1
        dp[2]=2
        
        for i in range(3,n+1):
            dp[i]=dp[i-2] +dp[i-1]
        
        return dp[n]
        
        
opt = Solution()
print(opt.climbStairs(n = 2))
