import java.util.Scanner;
public class PrintGrade{
    public static void main(String[] args){
        Scanner input  = new Scanner(System.in);
       int sc;
       System.out.println("please enter your score:");
       sc = input.nextInt();
       while (sc!=999){
           //printGrade3(sc);
           String s=printGrade3s(sc);
           System.out.println(s);
           System.out.println("please enter your score:");
           sc = input.nextInt();
       }
       /*固定次数循环
        
       for(int i=0;i<3;i++){
           System.out.println("please enter your score:");
           sc = input.nextInt();
           printGrade3(sc); //调用方法
       }*/
       
       
    }
    public static String printGrade3s(int score){
        if (score<0 || score>100){
            return"The score is invaild.";
        }
        else if (score<40){
            return"The corresponding grade is F.";
        }
        else if(score<70){
            return"The corresponding grade is B.";
        }
        else {
            return"The corresponding grade is E.";
        }
    }
}