import java.util.Scanner;

public class Main_yukicoder211 {
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int k = sc.nextInt();

		int[] d1 = {2, 3, 5, 7, 11, 13};
		int[] d2 = {4, 6, 8, 9, 10, 12};

		int ret = 0;
		for (int i = 0; i < 6; i++) {
			for (int j = 0; j < 6; j++) {
				if ((d1[i] * d2[j]) == k) {
					ret++;
				}
			}
		}
		
		System.out.println((double)ret / 36);
		sc.close();
	}
}