import java.util.ArrayList;
import java.util.Scanner;

public class Main {
		public static int exception(int h,int w){
			int result = 0;
			if(1 <= h && h <= 300 && 1 <= w && w <= 300){ //??????????????????(??\????¶???????)
				result = 2;
			}
			else if(h == 0 && w == 0){
				result = 1; //0,0??\?????§??\???????????????
			}
			else{
				System.out.println("1~300????????§.???????????????.");
				result = 0;
			}
			return result;
		}
		public static void main(String[] args) {
			/**
			 * ?????°?????£?¨?
			 */
			int a = 0;
			int t = 0, inc = 0;
			int h = 0,w = 0; //height:h width:w
			int x = 0;
			/**
			 * ???????????£?¨?
			 */
			ArrayList<String> st = new ArrayList<String>();
			ArrayList<Integer> parse = new ArrayList<Integer>();
			/**
			 * ????¨???????????????\???
			 */
			Scanner scan = new Scanner(System.in);
			while(a == 0){
			for (t = 0; t < 2; t++){ //??´??°2???????????????
			st.add(scan.next());
			}
			h = Integer.parseInt(st.get(inc));
			w = Integer.parseInt(st.get(inc+1));
			parse.add(h);
			parse.add(w);
			if(exception(h,w) == 1){ //h=w=0?????¨??????????????????????????????
				break;
			}
			else if(exception(h,w) == 0){ //??????????????????????????????.
				System.exit(0);
			}
			inc = inc + 2; //???????????§?????°
			}
			/**
			 * ??????
			 */
			for(int n= 1; n < ((parse.size())/2) ; ++n){ //???????????°??????
			 for(int i = 1; i < parse.get(2*(n-1))+1; ++i){ //hight
				for(int j = 1; j < parse.get(2*n-1)+1; ++j){ //width
				if((i + j) % 2 == 0){
					System.out.print("#");
				}
				else if((i + j) % 2 != 0 ){
					System.out.print(".");
				}
				}
				System.out.println("");
			 }
			 System.out.println("");
			}
		}
	}
/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