import java.io.*;
public class Grade{
	char getGrade(int n){
		n=n/10;
		char c='\u0000';
		switch(n){
			case 0:
			case 1:
			case 2:
			case 3:
			case 4:
			case 5:c='E';break;
			case 6:c='D';break;
			case 7:c='C';break;
			case 8:c='B';break;
			case 9:
			case 10:c='A';break;
			default:c='\u0000';
		}
		return c;
	}
	public static void main(String[] args){
		Grade a=new Grade();
		int n=-1;
		char c='\u0000';
		byte[] bt=new byte[3];
		System.out.print("請輸入一個成績（0~100）：");
		try{
			System.in.read(bt);
		}catch(IOException e){}
		String s = new String(bt);
		try{
			n=Integer.parseInt(s.trim());
		}catch (NumberFormatException e){
			System.err.println("數據格式不正確");
			System.exit(1);
		}
		c=a.getGrade(n);
		if (c == '\u0000')
			System.out.println("成績超出范圍");
		else
			System.out.println("你的成績為 "+c);
		
	}
}