#include<bits/stdc++.h>
using namespace std;

int main(){
    int k;
    cin >> k;
    
    int cnt=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++){
            if(a[i]*b[j] == k) cnt++;
        }
    }
    double ans = cnt/36.0;
    printf("%.10f", ans);
}