#include <bits/stdc++.h>
using namespace std;

long long candy[100];
int main() {
    candy[1] = 1;
    candy[2] = 2;
    for (int i = 3; i < 100; i++) {
        candy[i] = candy[i - 1] + candy[i - 2];
    }
    int n;
    while (cin >> n) {
        cout << candy[n] << endl;
    }
}