import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		String a = sc.next();
		String b = sc.next();
		if (judge(a)==true && judge(b)==true) {System.out.println("OK");}
		else {System.out.println("NG");}
	}
	static boolean judge (String s) {
		boolean b = false;
		for (int i=0; i<=12345; i++) {
			if (s.equals(String.valueOf(i))) {b = true;}
		}
		return b;
	}
}