#include <bits/stdc++.h>

using namespace std;

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

    int a[] = {2,3,5,7,11,13}, b[] = {4,6,8,9,10,12};

    int cnt = 0;

    for (int i = 0; i < 6; ++i) for (int j = 0; j < 6; ++j) {
        if (a[i] * b[j] == K) cnt++;
    }

    printf("%.14f\n", cnt / 36.0);
}