import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

import numpy as np

W,H,C = read().split()
W,H = map(int,(W,H))

A = np.empty((H,W),'U1')

if C == b'B':
    x,y = 'BW'
else:
    x,y = 'WB'
A[::2,::2] = x
A[1::2,1::2] = x
A[1::2,::2] = y
A[::2,1::2] = y

print('\n'.join(''.join(row) for row in A.astype(str)))