import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

class Main {

	public static void main(String[] args) {
	
		Scanner sc = new Scanner(System.in);
		
		ArrayList<Integer> height = new ArrayList<Integer>();
        ArrayList<Integer> width = new ArrayList<Integer>();
        //??\???????????????????¨??????????????´?????????¬??????????????????

        int H,W;
        //??\?????????????????????????????£??\???????????°?????°????????????????????????????????????????????????
         
        while(true){
            H = sc.nextInt();
            W = sc.nextInt();
             
            if(H == 0 && W == 0)
                break;
             
            height.add(H);
            width.add(W);
             
        }
        //??\??????????????°????????¨???????????\????????¨????????????height?????????width???????´???????
        
        int countH = 0;
        int countW = 0;
        //height??¨width???????´??????´????????¨????????°
        int t;
        
        for(countH = 0; countH < height.size(); countH++)
        {
        	//????????????????????\????????????????????°??????????????§????????¢?????????????????¨?????°?????????
        	for(int i = 0; i < height.get(countH); i++)
            {
        		//????????°??????????????????????????????????????§????????????
        		switch(i % 2)
        		{
        		case 0:for(t = 0; t < width.get(countW); t++)
        		{
        			switch(t % 2)
        			{
        			case 0:System.out.print("#");
        			break;
        			
        			case 1:System.out.print(".");
        			break;
        			}
        			if(t == width.get(countW) - 1)
                		System.out.println("");	
        			
        		}
        		break;
        		
        		case 1:for(t = 0; t < width.get(countW); t++)
        		{
        			switch(t % 2)
        			{
        			case 0:System.out.print(".");
        			break;
        			
        			case 1:System.out.print("#");
        			break;
        			}
        			if(t == width.get(countW) - 1)
                		System.out.println("");	
        		}
        		break;
        		
            		}
            	}
        	System.out.println("");
        	countW++;
        	//?¬????????????¢??¨??????????????????????????????????????????????????????
        	//countW??????????¶????????¬????????????¢????¨???????????????´???????????????
            }
        }

	}
/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