import java.io.IOException;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) throws Exception	{
		// TODO ?????????????????????????????????????????????
           Scanner sc = new Scanner(System.in);
           int a,b,c,d,e;
           a=1;b=1;e=1;
           while(a!=0||b!=0){
        	   a = sc.nextInt();
        	   b = sc.nextInt();
        	   c=1;d=1;
        	   if(e!=1){
        		   System.out.println();
        	   }
        	   while(c<=a){
        		   while(d<=b){
        			   if((d+c)%2==0){
        				   if(d!=b){
        					   System.out.print("#");
        				   }else{
        					   System.out.println("#");
        				   }
        			   }
        			   if((d+c)%2==1){
        				   if(d!=b){
        					   System.out.print(".");
        				   }else{
        					   System.out.println(".");
        				   }
        			   }
        			   d=d+1;
        		   }
        		   d=1;
        		   c=c+1;
        	   }
        	   c=1;
        	   e=e+1;
           }
	}

}
/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