import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

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