W, H, C = input().split()
W = int(W)
H = int(H)

row = [0 if i %2 == 0 else 1 for i in range(W)]
rows = []
for _ in range(H):
    rows.append(row)
    row = list(map(lambda x: (x + 1) % 2, row))

pattern = ["B", "W"] if C == "B" else ["W", "B"]

for r in rows:
    print("".join(list(map(lambda x: pattern[x], r))))