# 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|
    if C == "B"
        (i + 1).odd?? str = "BW": str = "WB"
        puts (str * width)[0, (width - 1)]
    elsif C == "W"
        (i + 1).odd?? str = "WB": str = "BW"
        puts (str * width)[0, (width - 1)]
    end
end