#include <bits/stdc++.h>
using namespace std;
int f(int x)
{
    if (x == 0 || x == 1)
        return 1;
    return f(x - 1) + f(x - 2);
}
int main()
{
    int x;
    while (cin >> x)
        cout << f(x) << "\n";
    return 0;
}