import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int w = sc.nextInt();
		int h = sc.nextInt();
		String c = sc.next();
		if (c.equals("B")) {
			for (int i=0; i<h; i++) {
				for (int j=0; j<w; j++) {
					int temp = i+j;
					if (temp%2==0) {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++) {
					int temp = i+j;
					if (temp%2==0) {System.out.print("W");}
					else {System.out.print("B");}
				}
				System.out.println();
			}
		}
	}
}