#include<bits/stdc++.h> using namespace std; int main(){ int a=1,b=1,c,k; cin >> k; if(k == 1 || k == 2){ cout << "1"; }else{ for(int i = 1;i <= k-2;i++){ c = a+b; a = b; b = c; } cout << c; } return 0; }