enum Color{
	BLACK,WHITE;
}

class Paper{
	final int width;
	final int height;
	final Color color;
	String line1 = "";
	String line2 = "";
	
	public Paper(int i,int j,String s){
		this.width = i;
		this.height = j;
		if(s.equals("B")){
			this.color = Color.BLACK;
		}
		else{
			this.color = Color.WHITE;
		}
	}
	
	public void show(){
		makeLine();
		reverse();
		
		for(int i = 0;i < height;i++){
			if(i%2 == 0){
				System.out.println(line1);
			}
			else{
				System.out.println(line2);
			}
		}
	}
	
	public void makeLine(){
		String s1,s2;
		
		if(this.color.equals(Color.BLACK)){
			s1 = "B";
			s2 = "W";
		}
		else{
			s1 = "W";
			s2 = "B";
		}
		
		for(int i = 0;i < this.width;i++){
			if(i%2 == 0){
				line1 += s1;
			}
			else{
				line1 += s2;
			}
		}
	}
	
	public void reverse(){
		String tmp = line1;
		tmp = tmp.replaceAll("B","t");
		tmp = tmp.replaceAll("W","B");
		tmp = tmp.replaceAll("t","W");
		line2 += tmp;
	}
}

public class No_82{
	public static void main(String[] args){
		java.util.Scanner sc = new java.util.Scanner(System.in);
		
		Paper paper = new Paper(sc.nextInt(),sc.nextInt(),sc.next());
		
		paper.show();
	}
}