#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(n); i++)

int dice1[6] = { 2,3,5,7,11,13 };
int dice2[6] = { 4,6,8,9,10,12 };

int main() {
    int K; cin >> K;
    int x = 0;
    rep(i, 6) rep(j, 6) if (K == dice1[i] * dice2[j]) x++;
    cout << fixed << setprecision(13) << (double(x) / 36.) << endl;

    return 0;
}