w,h,c=input().split()
w=int(w)
h=int(h)
s=[[0]*w for i in range(h)]
for i in range(h):
	for j in range(w):
		s[i][j]=(i+j)%2
	print("".join([(c+"BW"[c=="B"])[s[i][j]] for j in range(w)]))