#include <iostream> using namespace std; int main() { int n; cin >> n; int dp[51]; dp[1] = 1; dp[2] = 2; for (int i = 3; i <= n; ++i) { dp[i] = dp[i-1] + dp[i-2]; } cout << dp[n] << endl; return 0; }

#include<bits/stdc++.h> using namespace std; long long x[51]; int n; int main(){ cin>>n; x[1]=1; x[2]=2; for(int i=3;i<=n;i++){ x[i]=x[i-1]+x[i-2]; } cout<<x[n]; return 0; }