#include <iostream>

using namespace std;

int main() {
  int a[6]={2, 3, 5, 7, 11, 13}, b[6]={4, 6, 8, 9, 10, 12}, k, cnt=0;
  cin >> k;

  for (int i=0; i<6; i++) {
    for (int j=0; j<6; j++) {
      if (a[i]*b[j]==k) cnt++;
    }
  }

  printf("%0.12lf\n", cnt/36.0);
  return 0;
}