import java.util.Scanner;
 
class Main {
    @SuppressWarnings("resource")
    public static void main(String[] args) {
    	//??£?¨?, ?????????
        StringBuilder sb=new StringBuilder("");
         
        Scanner n=new Scanner(System.in);
          
        int a=n.nextInt();
        int b=n.nextInt();
    	//????????¨???         
        //????????¶??°?????????#??????????§??????????????\???°?????????. ??????
        //????????¶??°??¨?\???°??§?????????  #  ??¨ . ????????????
        while (a!=0 || b!=0){
        	
        	for (int c = 0; c < a ; c++){
                for (int d = 0 ; d < b ; d++){
                	//????????¶??°
                    if(c % 2 == 0){
                    	//????????¶??°
                    	if(d % 2 == 0){
                        	sb.append("#");
                        //???????\???°
                        } else if(d % 2 == 1){
                        	sb.append(".");
                        }
                    //???????\???°
                    } else if(c % 2 == 1){
                    	//????????¶??°
                    	if(d % 2 == 0){
                        	sb.append(".");
                        //???????\???°
                        } else if(d % 2 == 1){
                        	sb.append("#");
                        }
                    }
                }
                //??????
                sb.append("\n");  
            }
            
            //??????
            System.out.println(sb);
            a=n.nextInt();
            b=n.nextInt();
            sb=new StringBuilder("");
        }
    }
}
/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