import java.util.*;

public class Run {
    public static void main (String arg[]) {
        Scanner scan = new Scanner(System.in);
        double ans = 0.0;
        int [] array1 = {2, 3, 5, 7, 11, 13};
        int [] array2 = {4, 6, 8, 9, 10, 12};
        int x;
        HashMap<Integer, Integer> M = new HashMap<>();
        for (int i = 0; i < array1.length; i++) {
            for (int j = 0; j < array2.length; j++) {
                x = array1[i] * array2[j];
                if (!M.containsKey(x)) M.put(x, 1);
                else M.put(x, M.get(x) + 1);
            }
        }
        int K = scan.nextInt();
        if (M.containsKey(K)) ans = ((double) M.get(K)) / (array1.length * array2.length);
        System.out.println(ans);
    }
}