#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<map>
#include<queue>
#include<string>
#include<numeric>
#include<sstream>
#include<cmath>
using namespace std;

int main(){
  int a[6] = {2,3,5,7,11,13};
  int b[6] = {4,6,8,9,10,12};
  int k; cin >> k;
  int cnt = 0;
  for(int i=0; i<6; i++) {
    for(int j=0; j<6; j++) {
      if(a[i]*b[j] == k) cnt++;
    }
  }
  printf("%.18lf\n", cnt*1.0/36);

  return 0;
}




//