S = input().split()
W = int(S[0])
H = int(S[1])
C = S[2]


def f(r, c):
    if (r + c) % 2 == 0:
        return C
    return 'B' if C == 'W' else 'W'


for i in range(H):
    s = ''.join(f(i, j) for j in range(W))
    print(s)