import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int w = sc.nextInt(), h = sc.nextInt();
		String s = sc.next(), a, b;
		if(s.charAt(0) == 'B'){
			a = "B";
			b = "W";
		} else {
			a = "W";
			b = "B";
		}
		for(int i = 0; i < h; i++){
			for(int j = 0; j < w; j++){
				if((i+j)%2 == 0){
					System.out.print(a);
				} else {
					System.out.print(b);
				}
			}
			System.out.println();
		}
	}
}