#include<iostream>
#include<iomanip>
#include<algorithm>
using namespace std;

int main(){
    int primeDice[6] = {2, 3, 5, 7, 11, 13};
    int compositeDice[6] = {4, 6, 8, 9, 10, 12};
    int K;
    double cnt = 0;
    cin >> K;
    
    for(int i = 0; i < 6; i++){
        for(int j = 0; j < 6; j++){
            if(primeDice[i] * compositeDice[j] == K) cnt++;
        }
    }
    cout << setprecision(13) << (cnt/36) << endl;
    return 0;
}