using System;

public class Program {
	public static void Main(string[] args) {
		int k = int.Parse(Console.ReadLine());
		int[] a = {2, 3, 5, 7, 11, 13};
		int[] b = {4, 6, 8, 9, 10, 12};
		int count = 0;
		for (int i = 0; i < a.Length; i++) {
			for (int j = 0; j < b.Length; j++) {
				if (a[i] * b[j] == k) {
					count++;
				}
			}
		}
		Console.WriteLine(count / (double)(a.Length * b.Length));
	}
}