#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())
#define indexOf(v,x) (find(all(v),x)-v.begin())




int main(){
	int sosu[]={ 2,3,5,7,11,13 };
	int gou[]={4,6,8,9,10,12};
	int k,c=0;
	cin>>k;
	rep(i,6)rep(j,6)if(sosu[i]*gou[j]==k)c++;
	printf("%.12f\n",c/36.0);
	return 0;
}