import java.util.*;

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

		int W = sc.nextInt(), H = sc.nextInt();
		String C = sc.next();
		
		String[][] mark = new String[W][H];
		
		String C2;
		
		if(C.equals("B")) {
			C2 = "W";
		} else {
			C2= "B";
		}
		
		for(int i = 0; i < H; i++) {
			for(int j = 0; j < W; j++) {
				if(i % 2 == 0 && j % 2 != 0) {
					mark[j][i] = C2;
				} else if(i % 2 != 0 && j % 2 == 0) {
					mark[j][i] = C2;
				} else {
					mark[j][i] = C;
				}
			}
		}
		
		for(int i = 0; i < H; i++) {
			for(int j = 0; j < W; j++) {
				System.out.print(mark[j][i]);
			}
			
			System.out.println();
		}
	}
}