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 color = sc.next();
		String itimatu[][] = new String[H][W];
		
		for(int i = 0;i < H;i++) {
			for(int j = 0;j < W;j++) {
				itimatu[i][j] = color;
				if(color.equals("B")) {
					color = "W";
				}else {
					color = "B";
				}
			}
			if(itimatu[i][0].equals("B")) {
				color = "W";
			}else {
				color = "B";
			}
		}
		
		for(int i = 0;i < H;i++) {
			for(int j = 0;j < W;j++) {
				System.out.print(itimatu[i][j]);
			}
			System.out.println();
		}
	}
}