#include<bits/stdc++.h>
using namespace std;

typedef long long int ll;
typedef unsigned long long int llu;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pair<int, int> > vii;

#define rrep(i, m, n) for(int i=m; i<n;  i++)
#define erep(i, n)    for(int i=1; i<=n; i++)
#define  rep(i, n)    for(int i=0; i<n;  i++)
#define rrev(i, m, n) for(int i=n-1; i>=m; i--)
#define erev(i, n)    for(int i=n; i>=1; i--)
#define  rev(i, n)    for(int i=n-1; i>=0; i--)
#define EACH(v)       (v).begin(), (v).end()
#define CNT(a, n, x)  (upper_bound(a, a+n, x)-lower_bound(a, a+n, x))
#define minup(m, x)   (m=min(m, x))
#define maxup(m, x)   (m=max(m, x))
#define mp            make_pair

#define INF 1000000000
#define MOD 1000000009
#define EPS 1E-8

int w, h;
char c;
char bw[] = {'B', 'W'};
int ch;

int main()
{
  cin >> w >> h;
  cin >> c;

  ch = (c=='B' ? 0 : 1);

  rep(i, h) rep(j, w) cout << bw[(ch + i + j) & 1] << (j==w-1 ? "\n" : "");

  return 0;
}