#include <bits/stdc++.h>

using namespace std;

int main(void) {
  int k;
  cin >> k;

  int p[6] = {2, 3, 5, 7, 11, 13};
  int c[6] = {4, 6, 8, 9, 10, 12};
  int cnt = 0;
  for (int i = 0; i < 6; i++) {
    for (int j = 0; j < 6; j++) {
      cnt += p[i] * c[j] == k;
    }
  }

  printf("%.15f\n", cnt / 36.0);

  return 0;
}