import java.io.*;
import java.util.*;


public class Main_yukicoder446 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		char[] a = sc.next().toCharArray();
		char[] b = sc.next().toCharArray();

		if (isOK(a) && isOK(b)) {
			pr.println("OK");
		} else {
			pr.println("NG");
		}
	}

	private static boolean isOK(char[] a) {
		for (char c : a) {
			if (c < '0' || c > '9') {
				return false;
			}
		}

		int n = Integer.parseInt(String.valueOf(a));

		if (n == 0 && a.length > 1) {
			return false;
		}

		if (a[0] == '0' && n > 0) {
			return false;
		}

		if (n > 12345) {
			return false;
		}

		return true;
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}