#include <bits/stdc++.h>

using namespace std;

ifstream fin("kfib.in");
ofstream fout("kfib.out");

const double gr = (1 + sqrt(5)) / 2;

int n;

int main()
{
    fin >> n;

    long double nr = 2;

    if (n == 0)
        fout << 0;
    else if (n == 1)
        fout << 1;
    else if (n == 2)
        fout << 1;
    else if (n == 3)
        fout << 2;
    else
    {   for (int i = 4; i <= n; i++)
        {
            nr = round(nr * gr);
        }
    }

    fout << nr;
    fin.close();
    fout.close();
    return 0;
}