#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)

using namespace std;

typedef long long int lli;

int main() {
    int K;
    cin >> K;
    int prime[6] = {2, 3, 5, 7, 11, 13};
    int comp[6] = {4, 6, 8, 9, 10, 12};
    int cnt = 0;
    for (int p: prime) for (int c: comp) {
        if (p * c == K) cnt++;
    }
    cout << fixed << setprecision(15) << cnt / 36.0 << endl;
    return 0;
}