import java.util.Scanner;
class Main {
	public void kami() {
		Scanner sc = new Scanner(System.in);
		
		int H = sc.nextInt();
		int W = sc.nextInt();
		
		while(H != 0 || W != 0){
			
			for(int j = 1; j <= H; j++){
				for(int i = 1; i <= W; i++){
					if(j % 2 == 0){
						if(i % 2 == 0){
							System.out.print("#");
						}else{
							System.out.print(".");
						}
						
					}else{
						if(i % 2 == 0){
							System.out.print(".");
						}else{
							System.out.print("#");
						}
					}
				}
				System.out.println();
			}
			System.out.println();
			H = sc.nextInt();
			W = sc.nextInt();
		}
		
	
	}

	public static void main(String[] args) {

		new Main().kami();
	}

}
/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