#include <stdio.h>


int main(void)
{
	int h[300];
	int w[300];
	int i = -1,j,k,l;
	do{
		i++;
		scanf("%d%d", &h[i], &w[i]);
	} while (h[i] != 0 || w[i] != 0);
	for (j = 0; j <= i; j++){
		for (l = 0; l < h[j]; l++){
			for (k = 0; k < w[j]; k++) {
				if(l % 2 == 1 && k % 2 == 1)printf("#");
                                else if(l % 2 == 0 && K % 2 == 0)printf("#");
				else printf(".");
			}
			printf("\n");
		}
		if(j != i)printf("\n");
	}

	return 0;
}