using System;

class Program
{
    static void Main()
    {
        var a_str = Console.ReadLine();
        var b_str = Console.ReadLine();
        int n;
        
        if( int.TryParse(a_str,out n) == false )
            End(false);
        if( a_str[0] == '0' && n != 0 )
            End(false);
            
        if( int.TryParse(b_str,out n) == false )
            End(false);
        if( b_str[0] == '0' && n != 0 )
            End(false);
        
        End(true);
    }
    
    static void End(bool flag)
    {
        if( flag )
            Console.WriteLine("OK");
        else
            Console.WriteLine("NG");
        
        Environment.Exit(0);
    }
}