import java.util.Scanner; 
public class Main{ 
    public static void main(String[] args) { 
         Scanner scan = new Scanner(System.in); 
         int no = scan.nextInt();
         String name = scan.next();       
         String sex = scan.next();             
         String major = scan.next();
         int score = scan.nextInt();
         CollegeStudent c = new CollegeStudent(no, name, sex, major, score); 
         c.getGrade();
         no = scan.nextInt(); 
         name = scan.next();       
         sex = scan.next();       
         major = scan.next(); 
         String supervisor = scan.next(); 
         score = scan.nextInt();
         GraduateStudent g = new GraduateStudent(no, name, sex, major, supervisor, score); 
         g.getGrade();

         scan.close();  
    } 
}  

abstract class Student{ 
    private int no; 
    private String name; 
    private String sex; 
    private int score;
    public Student(int _no, String _name, String _sex, int _score){ 
        no = _no; 
        name = _name; 
        sex = _sex; 
        score = _score;
    } 
    public int getNo() { 
        return no; 
    } 
    public String getName() { 
        return name; 
    } 
    public String getSex() { 
        return sex; 
    } 
    public int getScore() {
    	return score;
    }
    public abstract void getGrade();
} 

class CollegeStudent extends Student{ 
    private String major; 
    public CollegeStudent(int _no, String _name, String _sex, String _major, int _score) { 
        super(_no, _name, _sex, _score); 
        major = _major; 
    } 
    public int getNo() { 
        return super.getNo(); 
    } 
    public String getName() { 
        return super.getName(); 
    } 
    public String getSex() { 
        return super.getSex(); 
    } 
    public String getMajor() { 
        return major; 
    } 
    public void getGrade() {
    	if(super.getScore()>=80 && super.getScore()<=100)
    		System.out.println("A");
    	else if(super.getScore()>=70 && super.getScore()<80)
    		System.out.println("B");
    	else if(super.getScore()>=60 && super.getScore()<70)
    		System.out.println("C");
    	else if(super.getScore()>=50 && super.getScore()<60)
    		System.out.println("D");
    	else 
    		System.out.println("E");
    }
} 

class GraduateStudent extends CollegeStudent{ 
    private String supervisor; 
    public GraduateStudent(int _no, String _name, String _sex, String _major,  String _supervisor, int  _score) { 
        super(_no, _name, _sex, _major, _score); 
        supervisor = _supervisor; 
    } 
    public void getGrade() {
    	if(super.getScore()>=90 && super.getScore()<=100)
    		System.out.println("A");
    	else if(super.getScore()>=80 && super.getScore()<90)
    		System.out.println("B");
    	else if(super.getScore()>=70 && super.getScore()<80)
    		System.out.println("C");
    	else if(super.getScore()>=60 && super.getScore()<70)
    		System.out.println("D");
    	else 
    		System.out.println("E");
    }
}