import java.util.Scanner;

public class yukicoder_82 {
	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		
		int w = stdIn.nextInt();
		int h = stdIn.nextInt();
		String c1 = stdIn.next();
		
		String c2 = (c1.equals("W")) ? "B" : "W";
		
		
		for (int i = 1; i <= h; i++) {
			for (int j = 1; j <= w; j++) {
				if (i % 2 == 1) {
					if (j % 2 == 1) {
						System.out.print(c1);
					} else {
						System.out.print(c2);
					}
				} else {
					if (j % 2 == 1) {
						System.out.print(c2);
					} else {
						System.out.print(c1);
					}
				}
			}
			System.out.println();
		}
	}
}