#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main(void){
  int k;
  cin >> k;
  int a[6] = { 2, 3, 5, 7, 11, 13};
  int b[6] = { 4, 6, 8, 9, 10, 12};
  double ans = 0;
  for(int i = 0; i < 6; i++){
    for(int j =0; j < 6; j++){
      if(a[i] * b[j] == k) ans++;
    }
  }
  ans /= 36;
  printf("%.20lf\n", ans);
  return 0;
}