
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner a = new Scanner(System.in);
		int h =1;
		int w = 1;
		
		while(h > 0 && w > 0){
			h = a.nextInt();
			w = a.nextInt();
			for(int i = 0;i < h;i++){
				for(int j = 0;j < w;j++){
					if((i % 2) == 0){
						System.out.print("#");
						System.out.print(".");
					}else{
						System.out.print(".");
						System.out.print("#");
					}
				}
				if(h != 0 && w != 0)
					System.out.println();
			}
			if(h != 0 && w != 0)
				System.out.println();
		}
	}

}