import java.util.Scanner;

public class Main{
	public static void main(String args[]){

		//????????¨?¨???????????????????
		Scanner sc = new Scanner(System.in);
		while(true){
			int intH = sc.nextInt();
			int intW = sc.nextInt();

			//??????H???W???0?????£???????????????????????????
			if((intH == 0) && (intW == 0)){
				break;
			}

			//??????
			//???????????????????????????
			for (int i = 0; i < intH; i++) {
				//String????????£?¨?????????????
				String A = "";
				//?¨?????????????????????????
				for (int j = 0; j < intW; j++) {
					//?????????????????¶??°??§?¨??????¶??°?????£??????
					if ((i % 2 == 0) && (j % 2 == 0)) {
						//String??????A???????????\??????
						A += "#";
					//???????????¶??°??§?¨?????\???°?????£??????
					}else if((i % 2 == 0) && (j % 2 == 1)){
						A += ".";

						//??????????\???°??§?¨??????¶??°?????£??????
					}else if((i % 2 == 1) && (j % 2 == 0)){
						A += ".";
						//??????????¨?????\???°?????£??????
					}else{
						A += "#";
					}
				}
				//?????????????????????
				System.out.println(A);
			}
			//???????????????????????£????????????
			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