#include <bits/stdc++.h>
using namespace std;
int p[157];

int main() {
  int a[] = {2, 3, 5, 7, 11, 13};
  int b[] = {4, 6, 8, 9, 10, 12};
  for (int i = 0; i < 6; i++) {
    for (int j = 0; j < 6; j++) {
      p[a[i] * b[j]]++;
    }
  }
  int k;
  cin >> k;
  double ans = p[k] / 36.0;
  cout << fixed << setprecision(14) << ans << endl;
  return 0;
}