import java.util.*;

public class Run {
    public static void main (String arg[]) {
        Scanner scan = new Scanner(System.in);
        byte W = scan.nextByte();
        byte H = scan.nextByte();
        if (W < 1||W > 50||H < 1||H > 50) System.exit(1);
        String C = scan.next();

        boolean flag;
        if (C.equals("W")) flag = true;
        else flag = false;
        for (byte i = 0; i < H; i++){
            for (byte j = 0; j < W; j++) {
                if (flag) System.out.printf("W");
                else System.out.print("B");
                flag = !flag;
            }
            if (W%2==0) flag = !flag;
            System.out.println();
        }
    }
}