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

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    int k; cin >> k;
    int a[] = {2,3,5,7,11,13};
    int b[] = {4,6,8,9,10,12};
    int c = 0;
    rep(i,6)rep(j,6) c += (a[i] * b[j] == k);
    cout.precision(17);
    cout << (double)c / 36 << endl;
}