W_, H_, C = gets.split
W = W_.to_i
H = H_.to_i
(0...H).each{|h|
    (0...W).each{|w|
        if (h+w)%2 == (C=="B" ? 0 : 1)
            print "B"
        else
            print "W"
        end
    }
    puts
}