// #define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
int main() {
    // Input
    int K;
    cin >> K;

    // Calculate
    int ans = 0;
    int p[6] = {2, 3, 5, 7, 11, 13};
    int c[6] = {4, 6, 8, 9, 10, 12};
    rep(i, 6) rep(j, 6) if (p[i] * c[j] == K) ++ans;

    // Output
    cout << fixed << setprecision(20);
    cout << ans / 36.0 << endl;
}