line = input().split()
w = int(line[0])
h = int(line[1])
c = line[2]

if c == 'B':
    colors = ['B', 'W']
else:
    colors = ['W', 'B']
    
ans = []
for i in range(h):
    tmp = ''
    if i % 2 == 0:
        for j in range(w):
            tmp += colors[j % 2]
    else:
        for j in range(w):
            tmp += colors[(j + 1) % 2]
    ans.append(tmp)
    
print('\n'.join(ans))