package yukicoder;

import java.util.Scanner;

public class Yuki82 {
	
	public static void main(String[] args) {
 
		Scanner scan = new Scanner(System.in);
		
		int w = scan.nextInt();
		int h = scan.nextInt();
		String c = scan.next();
		
		scan.close();
		
		for (int j = 1; j <= h; j++) {
			for (int i = 1; i <= w; i++) {
				test(c,j,i);
			}
			System.out.print("\n");
		}
	}
	
	private static void test(String str,int j,int i) {
		
		if("B".equals(str)){
			if(j%2 == 0) {
				if (i%2 == 0){
					System.out.print("B");
				} else { 
					System.out.print("W");
				}
			}else {
				if (i%2 != 0){
					System.out.print("B");
				} else { 
					System.out.print("W");
				}			
			}
		} else {
			if(j%2 == 0) {
				if (i%2 == 0){
					System.out.print("W");
				} else { 
					System.out.print("B");
				}
			}else {
				if (i%2 != 0){
					System.out.print("W");
				} else { 
					System.out.print("B");
				}			
			}			
		}
	}
}