#include <iostream>
#include <iomanip>
#include <unordered_map>

using namespace std;

int main() {
    std::unordered_map<int, int> ump;
    
    int sosuu[6] = {2, 3, 5, 7, 11, 13};
    int gousei[6] = {4, 6, 8, 9, 10, 12};
    
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 6; j++) {
            int tmp = sosuu[i] * gousei[j];
            ump[tmp]++;
        }
    }
    
    int k;
    
    cin >> k;
    
    double ans = ump[k] / 36.0;
    cout << setprecision(12) << ans << endl;
    
    return 0;
}