#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main() {



  int w,h;
  string c;
  cin >> w >> h >> c;

  //w,h vector生成
  vector< vector<string> > arr;
  arr.resize(h);
  for (int i = 0; i < h; i++) {
    arr[i].resize(w);
  }
  //arrにBW入力、出力
  string s;
  if (c == "B") { s = "W" ;}
  if (c == "W") { s = "B" ;}
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if ((i + j) % 2 == 0) {
        arr[i][j] = c;
      }else {
        arr[i][j] = s;
      }
      if (j == w - 1) {
        cout << arr[i][j] << "\n";
      }else{
        cout << arr[i][j];
      }
    }
  }


  return 0;
}