#include<bits/stdc++.h>
using namespace std;
int main(){
    int a[6]={2,3,5,7,11,13},b[6]={4,6,8,9,10,12},n;
    cin >> n;
    double ans=0;
    for(int i=0; i<6; i++)for(int j=0; j<6; j++){
        if(a[i]*b[j]==n) ans++;
    }
    ans/=36;
    cout << setprecision(15) << ans << endl;
}