(define (System.out.println x)
  (begin
    (display x)
    (newline)
  )
)

(define W "W")
(define B "B")

(define (CngClr C)
  (if (eq? C W)
      B
      W
  )
)

(let (
      (W (read))
      (H (read))
      (C (read))
     )
  (let loop((i 1) (j 1) (Color C))
    (begin
      (display Color)
      (if (= i W)
          (if (= j H)
                (newline)
                (begin
                  (newline)
                  (loop 1 (+ j 1) Color)
                )
          )
          (loop (+ i 1) j (CngClr Color))
      )
    )
  )
)