import java.util.Scanner;

public class Main {
    private static Scanner scan;

    public static void main(String[] args) {
        scan = new Scanner(System.in);

        while (true) {
            int x = scan.nextInt();
            int y = scan.nextInt();
            if (x == 0 && y == 0) {
                return;
            }
            for (int i = 0; i < x; i++) {
                for (int p = 0; p < y; p++) {
                    if ((i + p) % 2 == 0 ) {
                        System.out.print("#");
                    } else {
                        System.out.print(".");
                    }
                }
                System.out.print("\n");
            }
            System.out.print("\n");
        }
    }
}
/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