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

typedef long long LL;

int main(){
    int v1[] = {2,3,5,7,11,13};
    int v2[] = {4,6,8,9,10,12};
    int K;
    cin >> K;
    int cnt = 0;
    for(int i = 0; i < 6; i++){
        for(int j = 0; j < 6; j++){
            if(K == v1[i] * v2[j]) cnt++;
        }
    }
    cout << setprecision(13) << (double)(cnt) / 36 << endl;
    return 0;
}