import java.util.*;
public class Ichimatsu{
	public static void main(String[] arg){
		Scanner sc = new Scanner(System.in);
		int w,h;
		char b;
		w = sc.nextInt();
		h = sc.nextInt();
		b = sc.next().charAt(0);
		if(b == 'B'){
			for(int i = 0;i<h;i++){
				for(int j = 0;j<w;j++){
					if(((j%2 == 0) && (i%2 == 0))||((j%2 == 1)&&(i%2 == 1))){
						System.out.print("B");
					}else{
						System.out.print("W");
					}
				}
				System.out.println("");
			}
		}else{
			for(int i = 0;i<h;i++){
				for(int j = 0;j<w;j++){
					if(((j%2 == 0) && (i%2 == 0))||((j%2 == 1)&&(i%2 == 1))){
						System.out.print("W");
					}else{
						System.out.print("B");
					}
				}
				System.out.println("");
			}
		}
	}
}