import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int W = scan.nextInt();
		int H = scan.nextInt();
		String C = scan.next();
		scan.close();
		String temp = C;
		if(W % 2 == 0) {
			for(int i = 0; i < H; i++) {
				for(int j = 0; j < W; j++) {
					if(temp.equals("W")) {
						System.out.print(temp);
						temp = "B";
					}else {
						System.out.print(temp);
						temp = "W";
					}
				}
				System.out.println();
				if(temp.equals("W")) {
					temp = "B";
				}else {
					temp = "W";
				}
			}
		}else {
			for(int i = 0; i < H; i++) {
				for(int j = 0; j < W; j++) {
					if(temp.equals("W")) {
						System.out.print(temp);
						temp = "B";
					}else {
						System.out.print(temp);
						temp = "W";
					}
				}
				System.out.println();
			}
		}
	}
}