package codeup100;

import java.util.Scanner;

public class c1068 {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

int score = sc.nextInt();

sc.close();

// 풀이방법 2가지

// 첫번째 : if문

if(score >=90 && score <=100){

System.out.println("A");

}else if(score >=70 && score < 90){

System.out.println("B");

}else if(score >=40 && score < 70){

System.out.println("C");

}else{

System.out.println("D");

}

// 두번째 : switch문

switch (score/10) {

case 10 :

case 9 :

System.out.println("A");

break;

case 8 :

case 7 :

System.out.println("B");

break;

case 6 :

case 5 :

case 4 :

System.out.println("C");

break;

case 3 :

case 2 :

case 1 :

System.out.println("D");

break;

default :

System.out.println("D");

}

}

}