#coding: UTF-8

import sys
from math import pi
from collections import deque
from functools import reduce

### defs ###

### main ###
W,H,C = sys.stdin.readline().strip('\r\n').split()
W = int(W)
H = int(H)
moyou={'B':['BW','WB'], 'W':['WB','BW']}
for i in range(H):
	cnt = W//2
	s = moyou[C][i%2]*cnt
	if(W%2==1):
		s = s + moyou[C][i%2][0]
	print(s)