import java.util.*;

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 b = "";
    String w = "";
    for(int i = 0; i < W; i++) {
      if(i % 2 == 0) {
        b += "B";
        w += "W";
      } else {
        b += "W";
        w += "B";
      }
    }
    if(c.equals("B")) {
      for(int i = 0; i < H; i++) {
        if(i % 2 == 0) {
          System.out.println(b);
        } else {
          System.out.println(w);
        }
      }
    } else {
      for(int i = 0; i < H; i++) {
        if(i % 2 == 0) {
          System.out.println(w);
        } else {
          System.out.println(b);
        }
      }
    }
  }
}