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