import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int K = sc.nextInt();
		
		double[] answer = new double[201];
		for(final int p : new int[]{2,3,5,7,11,13}){
			for(final int q : new int[]{4,6,8,9,10,12}){
				answer[p * q] += 1 / 36.0;
			}
		}
		
		System.out.printf("%.14f\n", answer[K]);
	}
	
}