import java.util.Scanner;


public class Main {
//????????¨???????????????	
	static void print(boolean ln, boolean even){
		char a;
		if(even == true){
			a = '#';
		}else{
			a = '.';
		}
		if(ln == true){
			System.out.println(a);
		}else{
			System.out.print(a);
		}
	}
//??¶??°?\???°??§??¨??????????????´	
	static boolean judge(int num){
		if(num % 2 == 0){
			return true;
		}else{
			return false;
		}
	}
	
	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		
		Scanner sc = new Scanner(System.in);
		while(true){
//??¨??¢???H,W????¨????		
	//?????°H????¨????		
		int H = sc.nextInt();
	//?????°W????¨????
		int W = sc.nextInt();
//??????????????\?????????????????????
		if(H == 0 && W == 0){
			break;
		}
		
//??¨?????????
	//???????????°???????????????		
		for(int i = 0; i < H; i++){
			//?¨?????????°???????????????
			for(int j = 0; j < W; j++){
				//??????????????????????????????
				if(j == W -1){
					print(true, judge(i + j + 2));
				}else{
					print(false, judge(i + j + 2));
				}
			}
		}
//??¨?????????
	//??????????????????			
		System.out.println("");
		}
		sc.close();
	}
}
/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