#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);
}