using System;

namespace ITP1_5_C {
    class Program {
        static void Main(string[] args) {
            while(true) {
                string[] s = Console.ReadLine().Split(' ');
                int H = int.Parse(s[0]), W = int.Parse(s[1]);
                if(H == 0 && W == 0) break;
                string a = "";
                for(int i = 0; i < H; i++) {
                    for(int j = 0; j < W; j++) {
                        if(i == 0 || i % 2 == 0) {
                            if(j == 0 || j % 2 == 0) {
                                a = a.Insert(a.Length, "#");
                            } else {
                                a = a.Insert(a.Length, ".");
                            }
                        } else {
                            if(j == 0 || j % 2 == 0) {
                                a = a.Insert(a.Length, ".");
                            } else {                               
                                a = a.Insert(a.Length, "#");
                            }
                        }                       
                    }
                    Console.WriteLine(a);
                    a = "";
                }
            }
        }
    }
}