import java.util.*;
import java.math.*;
import java.io.*;
 
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int w = sc.nextInt();
		int h = sc.nextInt();
		int sb = sc.next().toCharArray()[0] == 'B'?0:1;
		
		for(int i = 0; i < h; i++) {
			for(int j = 0; j < w; j++) {
				System.out.print(((i + j + sb) % 2 == 0?'B':'W'));
			}
			System.out.println();
		}
	}
}