

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int h = scan.nextInt();
		int w = scan.nextInt();
		int i,j;
		char a,b,tmp;
		a = '#';
		b = '.';
		while(h!=0) {
			for(i=1;i<=h;i++) {
				for(j=1;j<=w;j++) {
					if(i%2 != 0) {
						System.out.print(a);
					}else {
						System.out.print(b);
					}
					tmp = a;
					a = b;
					b = tmp;
				}
				System.out.println();
			}
			System.out.println();
			h = scan.nextInt();
			w = scan.nextInt();
		}
	}
}

