//Normal

#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

void print(auto a){
  cout << a;
}

void prints(auto a){
  cout << a << " ";
}

void prints(){
  cout << " ";
}

void printl(auto a){
  cout << a << endl;
}

void printl(){
  cout << endl;
}

void fix(int n){
  cout << fixed << setprecision(n);
}

int main(){
  vector<int> A = {2, 3, 5, 7, 11, 13};
  vector<int> B = {4, 6, 8, 9, 10, 12};
  int K; cin >> K;
  
  int sum = 0;
  for(int i = 0; i < 6; i++){
    for(int j = 0; j < 6; j++){
      if(A[i]*B[j] == K) sum++;
    }
  }
  
  double ans = (double)sum/36.0;
  
  fix(15);
  printl(ans);
  
  return 0;
}