import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        double[] ans = new double[201];
        int[] dice1 = new int[]{2, 3, 5, 7, 11, 13};
        int[] dice2 = new int[]{4, 6, 8, 9, 10, 12};
        for (int i = 0; i < 6; i++) {
            for (int j = 0; j < 6; j++) {
                ans[dice1[i] * dice2[j]] += 1.0 / 36;
            }
        }
        System.out.println(ans[k]);
    }
}