#include <bits/stdc++.h>
#define fastIO (cin.tie(0), cout.tie(0), ios::sync_with_stdio(false))
#define precise(i) fixed << setprecision(i)
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

int main() {
  fastIO;

  int W, H;
  cin >> W >> H;
  char c;
  cin >> c;

  char mark[2]{};
  if (c == 'W') {
    mark[0] = 'W';
    mark[1] = 'B';
  } else {
    mark[0] = 'B';
    mark[1] = 'W';
  }

  rep(h, H) {
    rep(w, W) cout << mark[(w + h) % 2];
    cout << '\n';
  }
}