#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstring>
#include <cctype>
#include <cmath>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <list>
#include <stdio.h>
#include <string.h>
#include <cstdlib>
#include <math.h>
#include <bitset>
#include <iterator>
#include <iomanip>
#include <sstream>
#define INF 2000000000
using namespace std;
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
#define sym cout<<"---------"<<endl;
#define ll long long
#define PL pair<long long, long long>
#define P pair<int,int>
#define mk make_pair
#define en endl
#define WHITE 0
#define BLACK 2
#define GRAY 1
#define RE return 0
#define int ll

int which[55][55];

signed main(){
  int w,h;
  char ch;
  cin>>w>>h;
  cin>>ch;
  
  if(ch=='B') which[1][1]=1;
  
  for(int i=1; i<=h; i++){
    for(int j=1; j<=w; j++){
      if(j==1){
        if(i==1) continue;
        which[i][j]=1-which[i-1][j];
        continue;
      }
      which[i][j]=1-which[i][j-1];
    }
  }
  
  for(int i=1; i<=h; i++){
    for(int j=1; j<=w; j++){
      if(which[i][j]) cout<<'B';
      else cout<<'W';
    }
    cout<<en;
  }
}