package main

import "fmt"

func main() {
	var w, h int
	var c string
	fmt.Scan(&w, &h, &c)

	bw := "BW"
	k := 0
	if c == "W" {
		k = 1
	}

	for j := 0; j < h; j++ {
		s := ""
		for i := 0; i < w; i++ {
			s += string(bw[(i+j+k)%2])
		}
		fmt.Println(s)
	}
}