import java.util.Scanner;
public class PrintGader {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Your score is：");
        int sc = input.nextInt();
        while (sc != 999) {//不固定次数的循环
             printGrader(sc);
             System.out.print("Your score is：");
             sc = input.nextInt();
        }
        /*固定次数循环：
        for (int i=0;i<3;i++){
            System.out.print("Your score is：");//类名首字母大写
            int sc = input.nextInt();
            printGrader(sc);//调用方法
        }*/
     }
    public static void printGrader(int score){
        if (score<0 || score>100){
            System.out.println("The score is invalid.");
        }
        else if(score < 40){
            System.out.println("The corresponding is F.");
        }
        else if(score < 70){
            System.out.println("The corresponding is B.");
        } 
        else {
            System.out.println("The corresponding is E.");
        }
    }
}