#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int k;
    cin >> k;
    int a[6] = {2,3,5,7,11,13};
    int b[6] = {4,6,8,9,10,12};

    int cnt = 0;
    rep(i,6)rep(j,6)if(a[i] * b[j] == k)cnt++;

    cout << fixed << setprecision(12) << (double)cnt / 36.0 << endl;

    return 0;
}