#include <bits/stdc++.h>

using namespace std;

int main()
{
  int A[] = {2, 3, 5, 7, 11, 13};
  int B[] = {4, 6, 8, 9, 10, 12};
  int K;
  cin >> K;
  int ret = 0;
  for(int i = 0; i < 6; i++) {
    for(int j = 0; j < 6; j++) {
      if(A[i] * B[j] == K) ++ret;
    }
  }
  cout << fixed << setprecision(15) << ret / 36.0 << endl;
}