#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <algorithm>
#include <unordered_map>
#include <math.h>
using namespace std;

int main()
{
    int N;
    while (cin >> N) {
        vector<int> dp(N + 1);
        dp[0] = 1; dp[1] = 1;
        for (int i = 2; i <= N; ++i) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        cout << dp[N] << endl;
    }

    return 0;
}