import java.util.Scanner;

public class No82 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int w = sc.nextInt();
        int h = sc.nextInt();
        String c = sc.next();

        String[] bw = new String[2];
        bw[0] = c;
        if (c.equals("B")) {
            bw[1] = "W";
        } else {
            bw[1] = "B";
        }

        String baseline = "";
        for (int x = 0; x < w + 1; x++) {
            baseline += (x % 2 == 0) ? bw[0] : bw[1];
        }

        String line0 = baseline.substring(0, w);
        String Line1 = baseline.substring(1, w + 1);

        for (int y = 0; y < h; y++) {
            if (y % 2 == 0) {
                System.out.println(line0);
            } else {
                System.out.println(Line1);
            }
        }

        sc.close();
    }

}