using System;

public class Test
{
	public static void Main()
	{
		var a = Console.ReadLine();
		var b = Console.ReadLine();
		
		string ans = "OK";
		int n = 0;
		
		if(a[0] != '0' && a !="0")
		{
			if(!Int32.TryParse(a, out n) || n > 12345) ans = "NG";
			if(b[0] != '0' && b !="0")
			{
				n = 0;
				if(!Int32.TryParse(b, out n) || n > 12345) ans = "NG";
			}
		}
		if(a[0] == '0' && a !="0") ans = "NG";
		if(b[0] == '0' && b !="0") ans = "NG";
		n = 0;
		if(!Int32.TryParse(a, out n) || n > 12345) ans = "NG";
		n = 0;
		if(!Int32.TryParse(b, out n) || n > 12345) ans = "NG";
		Console.WriteLine(ans);
	}
}