include <bits/stdc++.h>

define ll long long

using namespace std;

int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); ll dol; cin >> dol; ll pdiddy[dol + 10]; pdiddy[1] = pdiddy[2] = 1; for(ll i = 3; i <= dol; i++){ pdiddy[i] = pdiddy[i — 1] + pdiddy[i — 2]; } cout << pdiddy[dol]; return 0; }