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

using namespace std;

int main() {

    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    int k;
    cin >> k;
    vector<int> vecPrime{2, 3, 5, 7, 11, 13};
    vector<int> vecComposite{4, 6, 8, 9, 10, 12};
    vector<int> vecMulti;
    for (int i = 0; i < 6; ++i) {
        for (int j = 0; j < 6; ++j) {
            vecMulti.push_back(vecPrime.at(i) * vecComposite.at(j));
        }
    }
    double hitNum = static_cast<double>(count(vecMulti.begin(), vecMulti.end(), k));
    double ans = hitNum / 36;
    cout << setprecision(12) << ans << endl;
    return 0;
}