import java.util.*;
import java.lang.String;
public class No446{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		String a=sc.nextLine();
		String b=sc.nextLine();
		if(check(a)==true&&check(b)==true){
			System.out.println("OK");
		}else{
			System.out.println("NG");
		}
	}
	
	private static boolean check(String S){
		if(S.length()<0||S.length()>5){return false;}
		if(S.matches("^[0-9]+$")==false){return false;}
		int n=Integer.parseInt(S);
		if(n<0||12345<n){return false;}
		return true;
	}
	
}