import java.util.Scanner;

public class scoregrade {
    public static void main(String[] args) {
        for (int i =1; i>=0;i++){
            System.out.println("请输入第"+i+"个学生成绩");
            Scanner sc = new Scanner(System.in);
            Double score = sc.nextDouble();
            if (score > 0 && score<60){
                System.out.println("第"+i+"个学生等级为"+"C");
            }else if (score >= 60 && score <=80){
                System.out.println("第"+i+"个学生等级为"+"B");

            }else {
                System.out.println("第"+i+"个学生等级为"+"A");
            }
            if(score <0 || score>100){
                System.out.println("成绩输入有误，请重新输入");
                i--;
            }
        }
    }
}