inpt = raw_input().split()
W = int(inpt[0])
H = int(inpt[1])
C = inpt[2]
tile = []
if C == 'B': tile = ['B', 'W']
else: tile = ['W', 'B']
for i in range(0, H):
	s = ''
	for j in range(0, W):
		s = s + tile[(i+j)%2]
	print s