import java.util.Scanner;

public class Main {

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