#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    int P[6]={2,3,5,7,11,13};
    int M[6]={4,6,8,9,10,12};
    int count=0;
    
    for(int i=0; i<6; i++){
      for(int j=0; j<6; j++){
          if(P[i]*M[j]==n)
          count++;
      }
    }
    cout<<(double)count/36<<endl;
}