#include <iostream>

using namespace std;

int n, s = 0;

void f(int x)
{
    if (x >= n)
    {
        if (x == n) s ++ ;
        return;
    }

    f(x + 1);
    f(x + 2);
}

int main()
{
    cin >> n;

    f(0);

    cout << s << endl;

    return 0;
}

#include <iostream>

using namespace std;

int f(int n)
{
    if (n < 0) return 0;
    else if (n <= 2) return n;
    else return f(n - 1) + f(n - 2);
}

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

    cout << f(n) << endl;

    return 0;
}