let () =
  Scanf.scanf "%d %d %s\n" @@ fun w h c ->
  let k = if c = "B" then 0 else 1 in
  for i = 0 to h - 1 do
    for j = 0 to w - 1 do
      Printf.printf "%s" (if (i+j+k) mod 2 = 0 then "B" else "W")
    done;
    Printf.printf "\n"
  done;