import java.util.Scanner;
public class Dice2{
	public static void main(String[] arg){
		int[] dice1 = {2,3,5,7,11,13};
		int[] dice2 = {4,6,8,9,10,12};
		int k,sum=0;
		Scanner sc = new Scanner(System.in);
		k = sc.nextInt();
		for(int i = 0;i<6;i++){
			for(int j = 0; j<6;j++){
				if(dice1[i]*dice2[j] == k)sum++;
			}
		}
		System.out.println((double)sum/36.0);
	}
}