import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in)) {
            int a, b;
            while ((a = scanner.nextInt()) != 0 && (b = scanner.nextInt()) != 0) {
                for (int i = 0; i < a; i++) {
                    for (int j = 0; j < b; j++) {
                        if ((i % 2 == j % 2)) {
                            System.out.print("#");
                        } else {
                            System.out.print('.');
                        }
                    }
                    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