#include

using namespace std;

int climbStairs(int n) {

 if(n<=0){

  return 0;

 }

 else if (n <= 1) {

  return 1;

 }

 else{

  int steps[n+1];

  steps[0] = 1;

  steps[1] = 1;

  for (int i = 2; i <= n; i++) {

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

  }

 }

 return steps[n];

}

int main(){

 int n=3;

 cout<<climbStairs(n);

 return 0;

}