#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>

using namespace std;

int main(){
  int w, h;
  string c;
  cin >> w >> h >> c;

  if (c == "B"){
    for (int i = 0; i < h; ++i){
      for (int j = 0; j < w; ++j){
        if ((i + j) % 2 == 0){
          cout << "B";
        }else{
          cout << "W";
        }
      }
      cout << "\n";
    }
  }else{
    for (int i = 0; i < h; ++i){
      for (int j = 0; j < w; ++j){
        if ((i + j) % 2 == 0){
          cout << "W";
        }else{
          cout << "B";
        }
      }
      cout << "\n";
    } 
  }
  return 0;
}