#include<iostream>
using namespace std;
int main(){
    int s[]={2,3,5,7,11,13};
    int g[]={4,6,8,9,10,12};
    int k;cin>>k;
    int a=0;
    for(int i=0;i<6;i++){
        for(int j=0;j<6;j++){
            if(k==s[i]*g[j])a++;
        }
    }
    cout<<fixed<<a/36.0<<endl;
}