W,  H, C = map(str,input().split())
M = [0]*W

for i in int(H):
	for j in int(W):
		
		if C == 'B':
			M[j] = 'B'
			C = 'W'
		else:
			M[j] = 'W'
			C = 'B'
			
		print(M)