W,H,C=input().split()
W,H=map(int,(W,H))
#print(W,H,C)
idx=(1,-1)[C=='B']
txt=''
for _ in range(W):
    txt+=('','B','W')[idx]
    idx*=-1


for _ in range(H):
    new=''
    for x in txt:
        new+=('B','W')[x=='B']
    print(new)
    txt=new