import java.math.BigInteger;
import java.util.*;
class Main {

	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[] a = new int[] {2,3,5,7,11,13};
		int[] b = new int[] {4,6,8,9,10,12};
		int k = sc.nextInt();
		int count = 0;
		for(int i = 0; i < 6; i++) {
			for(int j = 0; j < 6; j++) {
				if(a[i] * b[j] == k)count++;
			}
		}
		
		System.out.printf("%.20f\n",count/36.0);
		
		
	}

	

	
	
	
}