import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String a = sc.next();
    String b = sc.next();
    String ans = "OK";
    if((a.charAt(0) == '0') && (a.length() > 1)) ans = "NG";
    if((b.charAt(0) == '0') && (b.length() > 1)) ans = "NG";
    try {
      int A = Integer.parseInt(a);
      int B = Integer.parseInt(b);
      if((A < 0) || (A > 12345)) ans = "NG";
      if((B < 0) || (B > 12345)) ans = "NG";
    } catch(NumberFormatException e) {
      ans = "NG";
    }
    System.out.println(ans);
  }
}