import java.util.Scanner;
//class chargrade
public class chargrade
{
public static void main(String [] args)
{
char grade ;
Scanner get = new Scanner(System.in);
grade = get.nextChar();
switch (grade)
{
case 'A': System.out.println("excellant");
break;
case 'B': System.out.println("GOOD");
break;
case 'C': System.out.println("THINK OK");
break;
case 'D': System.out.println("THINKING");
break;
case 'E': System.out.println("EXERSISE MORE");
break;
case 'F': System.out.println("FAILED");
break;
default: System.out.println("please enter A to E");
break;
}
}
}