#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
using ll = long long;
using namespace std;
const int INF = 1e9;

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

    int cnt[210] = {0};
    int a[] = {2, 3, 5, 7, 11, 13};
    int b[] = {4, 6, 8, 9, 10, 12};
    int sum = 0;
    rep(i, 6) rep(j, 6) {
        ++cnt[a[i] * b[j]];
    }
    printf("%.13f\n", cnt[k] / 36.0);

    return 0;
}