import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		int w = sc.nextInt(); int h = sc.nextInt();
		char upLeft = sc.next().charAt(0);
		
		for (int i=0; i<h; i++) {
			if (upLeft == 'B') {
				if (i%2 == 0) System.out.println(bwbw(w));
				else System.out.println(wbwb(w));
			}
			else {
				if (i%2 == 0) System.out.println(wbwb(w));
				else System.out.println(bwbw(w));
			}
		}
		
	}
	
	static String bwbw(int n) {
		StringBuilder sb = new StringBuilder();
		for (int i=0; i<n; i++) {
			if (i%2 == 0) sb.append("B");
			else sb.append("W");
		}
		return sb.toString();
	}
	static String wbwb(int n) {
		StringBuilder sb = new StringBuilder();
		for (int i=0; i<n; i++) {
			if (i%2 == 0) sb.append("W");
			else sb.append("B");
		}
		return sb.toString();
	}
	
	
}