using System;

namespace Test
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            while (true)
            {
                var inputs = Console.ReadLine().Split(' ');
                var H = int.Parse(inputs[0]);
                var W = int.Parse(inputs[1]);
                if (H==0 && W==0) return;

                const char blockA = '#';
                const char blockB = '.';
                var lineA = new char[W];
                var lineB = new char[W];
                MakeCheck(lineA, blockA, blockB);
                MakeCheck(lineB, blockB, blockA);

                for (int i = 0; i < H; i++)
                {
                    if ((i & 1) == 0) Console.WriteLine(lineA);
                    else Console.WriteLine(lineB);
                }
                Console.WriteLine();
            }
        }

        public static void MakeCheck(char[] str, char first, char second)
        {
            var togle = false;
            Array.ConvertAll(str, x =>
            {
                togle = !togle;
                if (togle) return first;
                else return second;
            });
        }
    }
}