#include<iostream>
#include<vector>
#include<algorithm>
#include<cstdio>
using namespace std;
int main(){
    int s[6] = {2,3,5,7,11,13},g[6] = {4,6,8,9,10,12},N,count=0;
    cin >> N;    
    for(int i=0;i<6;i++){
        if(!(N%s[i])){
            for(int j=0;j<6;j++){
                if(s[i]*g[j]==N){
                    count++;
                }
            }
        }
    }
    printf("%.15lf",(double)count/36);
    return 0;
}