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


int main(){

  int k;
  cin >> k;
  vector<int> ans(13*12, 0);
  int a[6] = {2, 3, 5, 7, 11, 13};
  int b[6] = {4, 6, 8, 9, 10, 12};
  for(int i=0; i<6; i++){
    for(int j=0; j<6; j++){
      ans[ a[i]*b[j]-1 ]++;
    }
  }

  printf("%.19f\n",ans[k-1]*1.0/36);

  return 0;
}