import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int k = in.nextInt();

        int[] sosu = {2, 3, 5, 7, 11, 13};
        int[] gousei = {4, 6, 8, 9, 10, 12};

        double count = 0.0;

        for(int i=0; i<6; i++) {
            for(int j=0; j<6; j++) {
                if(k == sosu[i] * gousei[j]) count++;
            }
        }

        System.out.println(count / 36.0);

        in.close();
    }
}