package 成绩等级;import java.util.*;public class 成绩等级 {    public static void main(String[] args) {        // TODO Auto-generated method stub        Scanner s = new Scanner(System.in);                int a;        a = s.nextInt();                if(a > 90)            System.out.println("A");        else if(a >= 75 && a <= 89)            System.out.println("B");        else if(a >= 60 && a <= 74)            System.out.println("C");        else            System.out.println("D");    }}