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 c = sc.next();
		sc.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";
				}
			}
		}
	}
}