#include <iostream>
using namespace std;

int main()
{
	int k;
	cin >> k;

	double cnt = 0;
	for (int i : {2, 3, 5, 7, 11, 13})
	{
		for (int j : {4, 6, 8, 9, 10, 12})
		{
			cnt += i * j == k ? 1 : 0;
		}
	}
	printf("%.12f", cnt / 36);
}