package main

import "fmt"

func main() {
	var w, h int
	fmt.Scan(&w, &h)
	var c string
	fmt.Scan(&c)
	var bstart bool
	if c == "B" {
		bstart = true
	}
	for i := 0; i < h; i++ {
		if i > 0 {
			if bstart {
				bstart = false
			} else {
				bstart = true
			}
		}
		row := "W"
		if bstart {
			row = "B"
		}
		for j := 1; j < w; j++ {
			if row[j-1] == 'B' {
				row += "W"
			} else {
				row += "B"
			}
		}
		fmt.Println(row)
	}
}