import java.util.Scanner;

public class Ameyuki {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		String A = s.nextLine();
		String B = s.nextLine();
		int a,b;
		s.close();
		
		try{
			a = Integer.parseInt(A);
			b = Integer.parseInt(B);
			if(a > 12345 || b > 12345||a < 0|| b < 0){
				a = Integer.parseInt("A");
			}else if(A.length() != Integer.toString(a).length() || B.length() != Integer.toString(b).length()){
				a = Integer.parseInt("A");
			}
			System.out.println("OK");
		}catch(NumberFormatException e){
			System.out.println("NG");
		}
	}

}