import java.util.Scanner;

public class Yukicoder82 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int W = sc.nextInt();
		int H = sc.nextInt();
		char C1 = sc.next().charAt(0);
		char C2 = C1 == 'B' ? 'W' : 'B';
		for (int y = 0; y < H; y++) {
			for (int x = 0; x < W; x++) {
				if ((x+y) % 2 == 0) System.out.print(C1);
				else System.out.print(C2);
			}
			System.out.println("");
		}
	}
}