import java.util.Scanner;

public class No82 {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int width = s.nextInt();
        int height = s.nextInt();
        String color1 = s.next();
        String color2 = color1.equals("B") ? "W" : "B";
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                if (i % 2 == 0 && j % 2 == 0 || i % 2 == 1 && j % 2 == 1) {
                    sb.append(color1);
                } else {
                    sb.append(color2);
                }
            }
            sb.append("\n");
        }
        System.out.print(sb.toString());
    }
}