package yukicoder;

import java.util.Scanner;

public class Q446 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		boolean correct = true;
		for (int t = 0; t < 2; ++t) {
			char[] s = sc.next().toCharArray();
			for (int i = 0; i < s.length; ++i) {
				if (s[i] - '0' > 9 || s[i] - '0' < 0)
					correct = false;
			}

			if (s.length >= 2 && s[0] - '0' == 0) {
				correct = false;
			}

			int digit = 0;
			if (correct) {
				for (int i = 0; i < s.length; ++i) {
					digit = 10 * digit + (s[i] - '0');
				}

				if (digit > 12345) {
					correct = false;
				}
			}
		}

		if (correct) {
			System.out.println("OK");
		} else {
			System.out.println("NG");
		}

		sc.close();

	}
}