#coding:utf-8

s=raw_input().split()
w=int(s[0])
h=int(s[1])
h1=h
n=s[2]
	
h_even=''
h_odd=''
while h:
	if h%2==1:
		for i in range(w):
			if i%2==0:
				h_even+=n
			else:
				if n=='B':
					h_even+='W'
				else:
					h_even+='B'

	else:
		for i in range(w):
			if i%2==1:
				h_odd+=n
			else:
				if n=='B':
					h_odd+='W'
				else:
					h_odd+='B'
	
	h-=1

h_even=list(h_even)	
h_odd=list(h_odd)

res=[]
for i in range(h1):
	if i%2==0:
		res.append(h_even[:w])
		del h_even[:w]
	else:
		res.append(h_odd[:w])
		del h_odd[:w]

for i in res:
	print ''.join(i)