import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

import static java.lang.System.in;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(in));
        String A = reader.readLine();
        String B = reader.readLine();
        if (validate(A) && validate(B)) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }

    private static boolean validate(String s) {
        boolean isNumber = true;

        if (s.length() >= 2 && s.charAt(0) == '0' ) {
            isNumber = false;
        } else {
            for (int i = 0; i < s.length(); i++) {
                if (!Character.isDigit(s.charAt(i))) {
                    isNumber = false;
                    break;
                }
            }
        }

        int upperBound = 12345;
        int lowerBound = 0;
        if (isNumber) {
            int number = Integer.parseInt(s);
            if (lowerBound <= number && number <= upperBound) {
                return true;
            } else {
                return false;
            }
        } else {
            return false;
        }

    }
}