import java.util.Scanner;

class Main {
  public static void main(String args[]) {
    Scanner sc = new Scanner(System.in);
    String cs0 = sc.nextLine();
    String cs1 = sc.nextLine();

    try {
      int a = Integer.parseInt(cs0);
      int b = Integer.parseInt(cs1);
      if (a < 12345 && b < 12345 && a < 0 && b < 0 &&  Integer.toString(a).length() <= 5 && Integer.toString(b).length() <= 5) {
        System.out.println("OK");
      }else{
        System.out.println("NG");
      }
    } catch (NumberFormatException e) {
      System.out.println("NG");
    }

  }
}