#include<iostream>
#include<cmath>
#include<algorithm>
#include<string>
#include<map>
using namespace std;
int sum(int n) {
    if (n < 2) {
        return 1;
    }
    return sum(n - 1) + sum(n - 2);
}
int main() {
    int n;
    while (cin >> n) {
        cout << sum(n) << endl;
    }
    return 0;
}