#include<iostream>

#define REP(i,a,b) for(int i=(int)(a);i<(int)(b);++i)

using namespace std;

int main(){
  int W, H;
  char C;
  cin >> W >> H >> C;
  char ls[2] = {'W', 'B'};
  int pos = (C == 'W' ? 0 : 1);
  REP(i, 0, H) {
    REP(j, 0, W) {
      if ((i + j) % 2) {
	cout << ls[1 - pos];
      } else {
	cout << ls[pos];
      }
    }
    cout << '\n';
  }
  return 0;
}