#include <bits/stdc++.h>
using namespace std;

int main() {
  double dice = 0;
  int comp[] = {4, 6, 8, 9, 10, 12};
  int prim[] = {2, 3, 5, 7, 11, 13};
  int ans;
  scanf("%d", &ans);
  for (int i = 0; i < 6; i++) {
    for (int j = 0; j < 6; j++) {
      if (ans == comp[i] * prim[i]) dice++;
    }
  }
  printf("%12f\n", dice / 36);
  return 0;
}