#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

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

  vector<int> v{2, 3, 5, 7, 11, 13};
  vector<int> w{4, 6, 8, 9, 10, 12};

  int k;
  cin >> k;
  int cnt = 0;

  REP (i, 6) REP (j, 6) if (v[i] * w[j] == k) ++cnt;
  cout << fixed << setprecision(20) << cnt / 36.0 << endl;
  
  return 0;
}