#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 s, s1, s2;
  cin >> W >> H >> s;
  if (s == "W")
    s1 = "B", s2 = "W";
  else
    s1 = "W", s2 = "B";

  rep(i, 0, H) {
    rep(j, 0, W) {
      if (j % 2)
        cout << s1;
      else
        cout << s2;
    }
    cout << endl;
    swap(s1, s2);
  }
  getchar();
}