import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {
	public static void main(String[] args) {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			while (true) {
				String buf = br.readLine();
				StringTokenizer st = new StringTokenizer(buf, " ");
				int H = Integer.parseInt(st.nextToken());
				int W = Integer.parseInt(st.nextToken());

				if (W == 0 && H == 0)
					break;
				if (H >= 300 && W >= 300)
					break;
				;
				for (int i = 1; i <= H; i++) {
					for (int j = 1; j <= W; j++) {
						if(i%2==0){
							if (j%2==0)
								System.out.print("#");
							else
								System.out.print(".");
						}else {
							if (j%2==0)
								System.out.print(".");
							else
								System.out.print("#");

						}
					}
					System.out.println();
				}
				System.out.println();
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}
}
/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