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