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

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

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