//{{{
#include <bits/stdc++.h>
using namespace std;
#define rep(...) repN((__VA_ARGS__,rep3,rep2,loop,~))(__VA_ARGS__)
#define loop(n) rep2(_loop_,n)
#define rep2(i,n) rep3(i,0,n)
#define rep3(i,begin,end) for(int i=(int)(begin),i##_end=(int)(end);i<i##_end;++i)
#define repN(a) repX a
#define repX(a0,a1,a2,x,...) x
typedef long long ll;
const int MOD = 1e9+7;
//}}}

int a[100];
int main(){
	int W, H;
	char C;
	cin >> W >> H >> C;

	rep(h, H){
		rep(w, W){
			cout << "BW"[(h + w + (C == 'W')) % 2];
		}
		cout << endl;
	}
	return 0;
}