#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int W, H;
  cin >> W >> H;
  char C;
  cin >> C;
  int p = 0;
  if (C == 'B') p = 1;
  vector<char> S = {'W', 'B'};
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      cout << S[p];
      p = 1 - p;
    }
    if (W % 2 == 0) p = 1 - p;
    cout << '\n';
  }
  return 0;
}