package yukicoder;

import java.util.Scanner;

public class Yuki211 {
	
	public static void main(String[] args) {
		
		Scanner scan = new Scanner(System.in);
		int k = scan.nextInt();
		scan.close();
		Double count = 0.0;
		
		int primeNumbers[] = {2,3,5,7,11,13};
		int compositeNumbers[] = {4,6,8,9,10,12};
		
		for (int i = 0; i < primeNumbers.length; i++) {			
			for (int j = 0; j < compositeNumbers.length; j++) {
				if( k == primeNumbers[i] * compositeNumbers[j]){
					count++;
				}
			}
		}
		double answer =  count / 36.0;
		System.out.println(answer);
		
	}
}