#include <iostream>
#include <stdio.h>
#include <vector>
#include <map>
#include <algorithm>

using namespace std;

int main(){
    double dice_a[6] = {2,3,5,7,11,13};
    double dice_b[6] = {4,6,8,9,10,12};
    double K;

    map<double,double> dice_map;

    for(int i = 0; i < 6; i++){
        for(int j = 0; j < 6; j++){
            dice_map[dice_a[i] * dice_b[j]]++;
        }
    }

    cin >> K;

    printf("%f",dice_map[K] / 36);
}