#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>

using namespace std;

int main() {
	int k;
	int dice1[6] = {2,3,5,7,11,13};
	int dice2[6] = {4,6,8,9,10,12};
	int product[300] = {};

	cin >> k;
	for (int i = 0; i < 6; i++) {
		for (int j = 0; j < 6; j++) {
			int p = dice1[i] * dice2[j];
			product[p]++;
		}
	}

	printf("%.13lf\n", 1.0 * product[k] / 36);
	return 0;
}