public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String grade =scanner.next();
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");
}
//write your code here......
}
}