#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<stdlib.h>
#include<vector>
#include<string>
#include<sstream>
#include<math.h>
using namespace std;


int main(){

  int w, h;
  char c;
  cin >> w >> h >> c;
  bool b = false;
  for(int i=0; i<h; i++){
    if( (c == 'B' && i%2 == 0)||(c == 'W' && i%2 == 1) ) b = true;
    else b = false;
    for(int j=0; j<w; j++){
      if( b ){
        if( j%2 == 0 ) cout << "B";
        else cout << "W";
      }else{
        if( j%2 == 0 ) cout << "W";
        else cout << "B";
      }
    }
    cout << endl;
  }

  return 0;
}