#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

int main() {
    int K;
    cin >> K;
    int dice1[] = {2, 3, 5, 7, 11, 13};
    int dice2[] = {4, 6, 8, 9, 10, 12};
    double cnt = 0.0;

    REP(i, 6) {
        REP(j, 6) {
            if (dice1[i] * dice2[j] == K) cnt++;
        }
    }
    cout << fixed << setprecision(13);
    cout << cnt / 36.0 << endl;
    return 0;
}