#include <iostream>
using namespace std;

int main () {
    int f [99];
    f[0] = 0;
    f[1] = 1;
    for (int i = 2; i < 99 /*???*/; i++)
        f[i] = f[i - 1] + f[i - 2];
    int n;
    while (cin >> n)
        cout << f[n] << endl;
    return 0;
}