import java.util.*;

class No0082{
	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 d;
		String temp = "";

		System.out.print(c);
		d = c;
		if(w != 1 && h != 1){
			for(int i = 0; i < h; i++){
				for(int j = 0; j < w; j++){
					if(d.equals("B")){
						System.out.print("W");
						d = "W";
					}else{
						System.out.print("B");
						d = "B";
					}
					if(j + 1 == w){
						temp = d;
					}
					if(i == 0 && j + 2 == w){
						temp = d;
						break;
					}
				}
				System.out.println();
				if(w % 2 == 0){
					if(temp == "B"){
						d = "W";
					}else{
						d = "B";
					}
				}
			}
		}
	}
}