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

int a[] = {2,3,5,7,11,13};
int b[] = {4,6,8,9,10,12};
int c[13*12+1];

int main(){
    int K;
    cin >> K;
    int t = 0;
    for(auto aa : a) for(auto bb : b){
        c[aa * bb]++; t++;
    }
    printf("%.15f", 1.*c[K]/t);
}