#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;

int main() {
  int w,h;
  char c;
  cin>>w>>h>>c;
  bool isB0=(c=='B');
  rep(i,h){
    bool isB=isB0;
    rep(j,w){
      if(isB) cout<<'B';
      else cout<<'W';
      isB=!isB;
    }
    cout<<endl;
    isB0=!isB0;
  }
  return 0;
}