import java.util.Scanner;


public class Main_yukicoder82 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int w = sc.nextInt();
        int h = sc.nextInt();
        char[] bw = new char[2];
        bw[0] = sc.next().charAt(0);
        bw[1] = bw[0] == 'B' ? 'W' : 'B';
        for (int i = 0; i < h; i++) {
        	StringBuilder sb = new StringBuilder();
        	for (int j = 0; j < w; j++) {
        		sb.append(bw[(i + j) % 2]);
        	}
        	System.out.println(sb);
        }

        sc.close();
    }
}