public class Solution {

public static int climbStairs(int n) {

int temp[] = {0,1,2};

if(n>=0&&n<=2){

return temp[n];

}

int dp[] = new int[n+1];

dp[0]=0;dp[1] = 1;dp[2]=2;

if (n>2) {

for (int i = 3; i <dp.length ; i++) {

dp[i]=dp[i-1]+dp[i-2];

}

}

return dp[n];

}

}