#include <bits/stdc++.h>
using namespace std;

int main() {
  int W, H;
  char C;
  cin >> W >> H >> C;
  char D = (C == 'B') ? 'W' : 'B';

  vector<vector<char>> V(H, vector<char>(W, C));
  for (int i = 0, ch = 1; i < H; i++) {
    for (int j = (ch) ? 1 : 0; j < W; j += 2) V.at(i).at(j) = D;
    for (int j = 0; j < W; j++) cout << V.at(i).at(j);
    ch = (ch) ? 0 : 1;
    cout << "\n";
  }
}