#include <bits/stdc++.h>

using namespace std;

template <class T>
void copy(vector<T> from, vector<T> to) {
  copy(from.begin(), from.end(), back_inserter(to));
}

template <class T>
void sort(vector<T> a) {
  sort(a.begin(), a.end());
}

template <class T>
void input_to(vector<T> a) {
  T a_i;
  cin >> a_i;
  a.push_back(a_i);
}

int main() {
  int w, h;
  char c;
  cin >> w >> h >> c;

  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (c == 'B') {
        if ((i + j) % 2 == 0) {
          cout << "B";
        } else {
          cout << "W";
        }
      } else {
        if ((i + j) % 2 == 0) {
          cout << "W";
        } else {
          cout << "B";
        }
      }
    }
    cout << endl;
  }
  cout << endl;
}