import java.io.*;
import java.util.*;

class Main211 {
	
	public static void out (Object o) {
		System.out.println(o);
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		int k = Integer.parseInt(br.readLine());
		int max = 200;
		int[] sum = new int[max];
		int[] dice1 = {2,3,5,7,11,13};
		int[] dice2 = {4,6,8,9,10,12};
		
		for (int d1 : dice1) {
			for (int d2 : dice2) {
				sum[d1 * d2]++;
			}
		}
		
		out((double)sum[k] / 36);
		
	}
}