import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		String A = scan.next();
		String B = scan.next();
		scan.close();
		if(isNumber(A) && isNumber(B)) {
			int a = Integer.parseInt(A);
			int b = Integer.parseInt(B);
			System.out.println("OK");
		}else {
			System.out.println("NG");
		}
	}
	public static boolean isNumber(String num) {
	    try {
	    	if(num.length() > 1 && num.substring(0, 1).equals("0")) {
	        	return false;
	        }
	        Integer.parseInt(num);
	        return true;
	        } catch (NumberFormatException e) {
	        return false;
	    }
	}
}