#include <bits/stdc++.h> using namespace std; int main() { int n,m,ans1=1,ans2=1,ans; cin>>n; m=1+n; if(n==1||n==2) { cout<<"1"; } else { for(int i=3;i<=n;i++) { ans=ans1+ans2; ans1=ans2; ans2=ans; } cout<<ans; } return 0; }