W,H,C = raw_input().split()
W,H = int(W),int(H)
for i in range(H):
	row = ''
	for j in range(W):
		if (i+j) % 2 == 0:
			if C == 'B':
				row+='B'
			else:
				row += 'W'
		else:
			if C == 'B':
				row+='W'
			else:
				row += 'B'
	print row