w, h, s = map(str, input().split())
w = int(w)
h = int(h)

if w == h == 1:
    print(s)

else:
    if s == 'B':
        s = 'BW' * (w*h//2)
    else:
        s = 'WB' * (w*h//2)
    
    s = [s[i:i+w] for i in range(0, len(s), w)]
    
    for i in s:
        print(i)