#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <sstream>
#include <functional>
#include <map>
#include <string>
#include <cstring>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <list>
#include <numeric>
using namespace std;
const double PI = 3.14159265358979323846;
const double EPS = 1e-12;
const int INF = 1<<25;
typedef pair<int,int> P;
typedef long long ll;
typedef unsigned long long ull;

int a[] = {2, 3, 5, 7, 11, 13}, b[] = {4, 6, 8, 9, 10, 12};
long double d[500];

int main(){
	for(int i = 0; i < 6; i++)
		for(int j = 0; j < 6; j++)
			d[a[i]*b[j]]+=1.0;
	int c;
	cin>>c;
	printf("%.99Lf\n", d[c]/36.0);
	return 0;
}