#include <iostream>
#include <vector>
using namespace std;

int main() {
    int K;
    cin >> K;
    vector<int> x, y;
    x = {2, 3, 5, 7, 11, 13};
    y = {4, 6, 8, 9, 10, 12};
    double ans = 0;
    for (int i = 0; i < 6; i++) {
        for ( int j = 0; j < 6; j++) {
            int a = x[i] * y[j];
            if (a == K) {
                ans++;
            }
        }
    }
    ans = ans / double(36);
    printf("%.20f\n", ans);
}