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

if C=="B":
    for h in xrange(H):
        row=""
        for w in xrange(W):
            if (h+w)%2==0:
                row+= "B"
            else:
                row+= "W"
        print row

else:
    for h in xrange(H):
        row=""
        for w in xrange(W):
            if (h+w)%2==0:
                row+= "W"
            else:
                row+= "B"
        print row