import java.util.Scanner;

public class pre {
    public static void main(String[] args) {

        Scanner s = new Scanner(System.in);
		int w = s.nextInt(),h = s.nextInt();
		String c = s.next();
		
		String[] str = new String[w*h];
		
		for(int i=0;i<w*h;i++){
			if(i >= w && i%w == 0 && str[i-1].equals("B") && w%2 == 0){
				str[i] = "B";
			}
			else if(i >= w && i%w == 0 && str[i-1].equals("W") && w%2 == 0){
				str[i] = "W";
			}
			else if(c.equals("B")){
				str[i] = c;
				c = "W";
			}
			else if(c.equals("W")){
				str[i] = c;
				c = "B";
			}
		}
		
		int cnt=0;
		
		for(int i=0;i<w*h;i++){
			if(cnt == w){
				System.out.println();
				cnt = 0;
				System.out.print(str[i]);
				cnt++;
			}
			else{
				System.out.print(str[i]);
				cnt++;
			}
		}
    }
}