#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<vector<char> > v;
  v.resize(n, vector<char>(m));
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) cin >> v[i][j];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if ((i + j) % 2 == 0 && v[i][j] == '.') {
        cout << "B";
        if (j == m - 1) cout << "\n";
      } else if ((i + j) % 2 == 1 && v[i][j] == '.') {
        cout << "W";
        if (j == m - 1) cout << "\n";
      } else {
        cout << "-";
        if (j == m - 1) cout << "\n";
      }
    }
  }
  return 0;
}
