import java.util.Scanner;

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

        for(int i=0; i<h; i++) {
            for(int j=0; j<w; j++) {
                if(c.equals("B")) {
                    System.out.print("B");
                    c = "W";
                } else {
                    System.out.print("W");
                    c = "B";
                }
            }
            System.out.println();
            if((w % 2) == 0) {
                if(c.equals("B")) {
                    c = "W";
                } else {
                    c = "B";
                }
            }
        }
    }
}