#include<iostream>
#include<stdio.h>
using namespace std;
int main(){
    int prime[6]={2,3,5,7,11,13};
    int comp[6]={4,6,8,9,10,12};
    int cnt=0,k;
    cin >> k;
    for(int i=0;i<6;i++){
        for(int j=0;j<6;j++){
            if(prime[i]*comp[j]>k)break;
            if(prime[i]*comp[j]==k)cnt++;
        }
    }
    printf("%.14f\n",(double)cnt/36.0);
}