*WH,C=input().split()
W,H=map(int,WH)
ans=[[C for i in range(W)] for j in range(H)]

c2 = "B" if C=="W" else "W"
for i in range(H):
    for j in range(W):
        if (i+j)%2:
            ans[i][j] = c2

for i in range(H):
    print(''.join(ans[i]))