import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner in = new Scanner(System.in);
		int h,w;
		
		h=in.nextInt();
		w=in.nextInt();
		
		while(h!=0 || w!=0){
			for(int i=0; i<h; i++){
				for(int j=0; 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();
			h = in.nextInt();
			w = in.nextInt();
		}
	}
}
/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