#include <bits/stdc++.h>
#define rep(i, ss, ee) for (int i = ss; i < ee; ++i)
using namespace std;

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int H, W;
  string C1, C2;
  cin >> W >> H >> C1;
  if (C1 == "W")
    C2 = "B";
  else
    C2 = "W";

  rep(i, 0, H) {
    rep(j, 0, W) {
      if ((i + j) % 2)
        cout << C2;
      else
        cout << C1;
    }
    cout << endl;
  }
  getchar();
}