dic = {True:'B', False:'W'}

W, H, C = raw_input().split()
W, H = int(W), int(H)
flag = True if C == 'B' else False
for i in xrange(H):
    s = ""
    for j in xrange(W):
        s += dic[flag]
        flag = not flag
    print s
    if W % 2 == 0:
        flag = not flag