#include<bits/stdc++.h>
using namespace std;
using Int = long long;
//INSERT ABOVE HERE
signed main(){
  Int w,h;
  char c;
  cin>>w>>h>>c;
  string s;
  s+=c;
  if(c=='B') s+='W';
  else s+='B';
  for(Int i=0;i<h;i++){
    for(Int j=0;j<w;j++)
      cout<<s[(i+j)&1];
    cout<<endl;
  }
  return 0;
}