#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed;
  int w, h;
  char c;
  cin >> w >> h >> c;
  char odd = (c=='B' ? 'W' : 'B');
  char even = (c=='B' ? 'B' : 'W');
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      cout << ((i+j)%2==0 ? even : odd);
    }
    cout << endl;
  }
  return 0;
}