H = []
W = []
cnt = 0
while 1:
	stdin = raw_input().split()
	h = int(stdin[0])
	w = int(stdin[1])
	if h == 0 and w == 0:
		break
	H.append(h)
	W.append(w)
	cnt += 1

str1 = '#.' * 150
str2 = '.#' * 150
for i in range(cnt):
	for j in range(H[i]):
		if(j%2 == 0):
			print str1[:W[i]]
		else:
			print str2[:W[i]]
	print ''
