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public partial class IntroductionToProgramming{
    public static void Main(){
        string[] line = System.Console.ReadLine().Split(' ');
 
        int h = int.Parse(line[0]);
        int w = int.Parse(line[1]);
 
        string es = string.Empty;
        string os = string.Empty;
        for (int i = 0; i < 300; i++)
        {
            es += i % 2 == 0 ? "#" : ".";
            os += i % 2 == 0 ? "." : "#";
        }
 
        while (!(h == 0 && w == 0))
        {
            for (int i = 0; i < h; i++ )
            {
                System.Console.WriteLine(i % 2 == 0 ? es.Substring(0, w) : os.Substring(0, w));
            }
            System.Console.WriteLine(string.Empty);
 
            string[] line2 = System.Console.ReadLine().Split(' ');
 
            h = int.Parse(line2[0]);
            w = int.Parse(line2[1]);
        }
    }
}
 