# 入力された値を受け取る
W, H, C = gets.chomp.split
width = W.to_i

# H行分出力する
H.to_i.times do |i|
    case C
    when "B" then
        (i + 1).odd?? str = "BW": str = "WB"
    when "W" then
        (i + 1).odd?? str = "WB": str = "BW"
    end
    # puts (str * width)[0..(width - 1)]
    puts (str * width)[0, width]
end