#include <iostream>
using namespace std;

int main(){
  int w,h;
  char c;
  cin >> w >> h >> c;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(c=='B'){if((i+j)%2==0)cout << 'B';else cout << "W";}else{if((i+j)%2==0)cout << 'W';else cout << "B";}
    }
    cout << endl;
  }
  return 0;
}