#include <bits/stdc++.h>

using namespace std;

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

  int n;
  cin >> n;
  int cnt = 0;
  for (int i = 0; i < 6; ++i) {
    for (int j = 0; j < 6; ++j) {
      if (a[i] * b[j] == n) cnt++;
    }
  }
  double ans = (double)cnt / 36;
  cout << fixed << setprecision(13) << ans << '\n';
  return 0;
}