import java.util.*;
import java.lang.NumberFormatException;

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

    String[] array = new String[2];
    array[0] = sc.next();
    array[1] = sc.next();

    try {
      for (String x : array) {
        if (x.startsWith("0") && x.length() > 1) {
           throw new NumberFormatException();
        }
        Integer.parseInt(x);
      }
    } catch(NumberFormatException e) {
      System.out.println("NG");
      return;
    }
      System.out.println("OK");
  }
}