
import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		outer: while (true) {
			int H = sc.nextInt();
			int W = sc.nextInt();

			if (H > 300 || H < 0 || W > 300 || W < 0) {
				System.out.println("数値の有効範囲は1 <= H,W <= 300です");
				continue outer;
			}

			if (H == 0 && W == 0) {
				break;
			}

			for (int i = 1; i <= H; i++) {
				for (int j = 1; j <= W; j++) {
					if (i % 2 == 1) {
						if (j % 2 == 1) {
							System.out.print("#");
						} else {
							System.out.print(".");
						}
					} else {
						if (j % 2 == 1) {
							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