import java.util.Scanner;

public class yukicoder_211 {
	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		int k = stdIn.nextInt();
		
		int[] sosu = {2, 3, 5, 7, 11, 13};
		int[] gosei = {4, 6, 8, 9, 10, 12};
		
		int count = 0;
		
		for (int i = 0; i < sosu.length; i++) {
			for (int j = 0; j < gosei.length; j++) {
				if (sosu[i] * gosei[j] == k) {
					count++;
				}
			}
		}
		
		System.out.println((double) count / 36);
	}
}