import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            int H = scanner.nextInt();
            int W = scanner.nextInt();
            if (H == 0 && W == 0) break;
            for (int h = 0; h < H; h++) {
                char c = (h % 2 == 0 ? '#' : '.');
                for (int w = 0; w < W; w++) {
                    System.out.print(c);
                    c = (c == '.' ? '#' : '.');
                }
                System.out.println("");
            }
            System.out.println("");
        }
    }
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz