
import java.util.*;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		StringBuilder sb = new StringBuilder();
		//sb.append("");// ??????????????\???????????????
		int h, w, c;
		c = 0;// ?????¶??§???????????°

		while (true) {
			h = scan.nextInt();// ????????????
			w = scan.nextInt();// ?¨??????????
			// h??¨w?????¨??????0????????£?????¨??????????????????????????????
			if ((h == 0) & (w == 0)) {
				break;
			}

			// for?????§????????????h??§????????????
			for (int count = 0; count < h; count++) {
				// for?????§?¨???????????????§????????????
				for (int count2 = 0; count2 < w; count2++) {
					// #???StringBuilder?????\????????????
					if (c % 2 == 0) {// C????????????0?????¨?????¨????????´?????§???????????????
						sb.append("#");
						c++;
					} else {
						sb.append(".");
						c++;
					}

				}
					sb.append("\n");
					c++;

			}
			System.out.println(new String(sb));
			System.out.println("");
			// StringBuilder????????????????????????
			sb.delete(0, sb.length());
			c = 0;// ?????¶??§???????????°????????????
		}

	}
}