/* -*- coding: utf-8 -*-
 *
 * 82.cc: No.82 市松模様 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int w, h;
  char cs[2];
  cin >> w >> h >> cs[0];

  cs[1] = (cs[0] == 'B') ? 'W' : 'B';

  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) putchar(cs[(x + y) & 1]);
    putchar('\n');
  }
  return 0;
}