more things

#include <bits/stdc++.h>
 using namespace std;
 typedef long long ll;

 ll f(ll n) {
  if (n == 1) return 1; if (n == 2) return 2; return f(n - 1) + f(n - 2);
 }
 
 int main(){
  ll n;
  cin >> n;
  cout << f(n) << endl;
 return 0;
 }