import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String grade = scanner.next();
//write your code here......
if (grade.equals("A")) {
System.out.println("优秀");
} else if (grade.equals("B")) {
System.out.println("良好");
} else if (grade.equals("C")) {
System.out.println("及格");
} else if (grade.equals("D")) {
System.out.println("不及格");
} else {
System.out.println("未知等级");
}
}
}

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