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.print("优秀");
}else if(grade.equals("B")){
System.out.print("良好");
}else if(grade.equals("C")){
System.out.print("及格");
}else if(grade.equals("D")){
System.out.print("不及格");
}else{
System.out.print("未知等级");
}
scanner.close();
}
}