#include<bits/stdc++.h>
using namespace std;
int get_num(int n);
int main(){
//z主要是解题思路
int n;
while(cin>>n){
int res = get_num(n);
cout<<res<<endl;
}
return 0;
}
int get_num(int n){
if(n==1||n==2)
return 1;
return get_num(n-1)+get_num(n-2);
}