public class No_211 {

	public static void main(String[] args) {
		java.util.Scanner sc = new java.util.Scanner(System.in);
		int num = sc.nextInt();
		sc.close();
		int[] sosu = { 2, 3, 5, 7, 11, 13 };
		int[] gosei = { 4, 6, 8, 9, 10, 12 };
		int count = 0;

		for (int i = 0; i < 6; i++) {
			for (int j = 0; j < 6; j++) {
				if (num == sosu[i] * gosei[j]) {
					count++;
				}
			}
		}

		System.out.println((double) count / 36);

	}

}