#include<bits/stdc++.h>
#define rep(i,a,n) for (int i = a;i < n;i++)
#define per(i,n,a) for (int i = n-1;i >= a;i--)
using namespace std;

int main() {
    int a[] = {2,3,5,7,11,13},b[] = {4,6,8,9,10,12},k,ans = 0;
    scanf("%d",&k);
    rep(i,0,6){
        rep(j,0,6){
            if(k == a[i]*b[j]){
                ans++;
            }
        }
    }
    printf("%.12f",ans/36.0);
}