\begin{array}{c} \color{#FFFFFFff}{H}\color{#E7E7E7ff}{o}\color{#CFCFCFff}{r}\color{#B7B7B7ff}{i}\color{#9F9F9Fff}{z}\color{#878787ff}{o}\color{#6F6F6Fff}{n} \end{array} $\\$

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

long long f(int n) {
    if (n == 1 || n == 2) 
        return 1;
    return f(n - 1) + f(n - 2);
}

int main() {
    int n; cin >> n;

    cout << f(n);
}