#include <bits/stdc++.h>
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repr(i, a, n) for (int i = n - 1; i >= a; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
template <typename T> void chmin(T &a, T b) { a = min(a, b); }
template <typename T> void chmax(T &a, T b) { a = max(a, b); }

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

  int w, h;
  char c;
  cin >> w >> h >> c;
  rep(i, 0, h) {
    rep(j, 0, w) {
      if ((i + j) % 2 ^ c == 'B')
        cout << "B";
      else
        cout << "W";
    }
    cout << endl;
  }
}