import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int w = sc.nextInt();
		int h = sc.nextInt();
		char c =sc.next().charAt(0);
		int k = c == 'B' ? 0 : 1;
		for(int i = 0 ; i < h ; i++) {
			for(int j = 0 ; j < w ; j++) {
				System.out.print((i + j + k) % 2 == 0 ? "B" : "W");
			}
			System.out.println();
		}
 	}
}