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