#include<stdio.h>
int main(void){
	int h = 1, w = 1, countah, countaw, counta=0;
	while (h != 0 && w != 0){


		scanf_s("%d", &h);
		scanf_s("%d", &w);


		for (countah = 1; countah <= h; countah++){

			for (countaw = 1; countaw <= w; countaw++){
				counta=counta++;
				if (counta % 2 != 0){
					printf("#");
				}

				else{
					printf(".");
				}


			}
			printf("\n");


		}

	}

	return 0;
}