#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);
  int w,h;cin>>w>>h;
  char c;cin>>c;
  if(c=='W'){
     rep(i,h){
      rep(j,w){
        (i%2==0 && j%2==0) || (i%2==1 && j%2==1) ? cout<<"W" : cout<<"B"; 
      }
      cout<<endl;
    }
  }else{
    rep(i,h){
      rep(j,w){
        (i%2==0 && j%2==0) || (i%2==1 && j%2==1) ? cout<<"B" : cout<<"W"; 
      }
      cout<<endl;
    }
  }
}