W, H, C = input().split()
W = int(W)
H = int(H)
for h in range(H):
    if (h & 1 and C == 'B') or (h % 2 == 0 and C == 'W'):
        print('WB' * (W // 2) + ('W' if W & 1 else ''))
    else:
        print('BW' * (W // 2) + ('B' if W & 1 else ''))