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

int main()
{
    int k;
    cin >> k;

    double cou = 0;
    int s[6] = {2,3,5,7,11,13};
    int g[6] = {4,6,8,9,10,12};
    for(int i = 0; i < 6; i++){
        for(int j = 0; j < 6; j++){
            if(k == s[i] * g[j]) cou++;
        }
    }
    
    cout << fixed << setprecision(12) << cou / 36 << endl;

    return 0;
}