#include <bits/stdc++.h> 
using namespace std;
#include <stdio.h>
#include <iomanip>
#include <iostream>
#include <string>
#include <algorithm>

int main(){
  int a, b;
  char design;
  cin >> a >> b >> design;
  vector<vector<char>> vec(b, vector<char>(a));
  for(int i=0;i<b;i++){
    for(int k=0;k<a;k++){
      	if(design=='W'){
        	if(((k%2==0)&&(i%2==0))||((k%2==1)&&(i%2==1))){
          	vec.at(i).at(k)='W';
        	}
        	else vec.at(i).at(k)='B';
      	}
      	else if(design=='B'){
        	if(((k%2==0)&&(i%2==0))||((k%2==1)&&(i%2==1))){
          	vec.at(i).at(k)='B';
        	}
        	else vec.at(i).at(k)='W';
      	}
       cout << vec.at(i).at(k);
    }
    cout << endl;
  }
}