#include <iostream>
#include <math.h>
#include <algorithm>
#include <functional>
#include <vector>
#include <typeinfo>
#include <climits>
#include <ctype.h>
#include <string>
#include <stdio.h>
using namespace std;
#define INIT cin.tie(0); ios::sync_with_stdio(false);
#define FOR(i, a, n) for (int i = a; i < n; i++)
#define REP(i, n) for(int i = 0; i < n; i++)

int main()
{
    INIT;

    int k;
    cin >> k;

    int A[6] = {2, 3, 5, 7, 11, 13};
    int B[6] = {4, 6, 8, 9, 10, 12};

    double cnt = 0;
    REP(i, 6){
        REP(j, 6){
            if(A[i] * B[j] == k) cnt++;
        }
    }

    double ans = cnt / 36;
    printf("%.12f", ans);

    return 0;
}