import math
M = list(map(str, input().split()))
n = int(M[0])
o = int(M[1])
p = math.ceil(n / 2)
for i in range(o):
    if (i + 1) % 2 == 1:
        if M[2] == "W":
            ans = "WB" * p
            print(ans[:n])
        if M[2] == "B":
            ans = "BW" * p
            print(ans[:n])
    else:
        if M[2] == "W":
            ans = "BW" * p
            print(ans[:n])
        if M[2] == "B":
            ans = "WB" * p
            print(ans[:n])