#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> P;
typedef pair<int,pair<int,int>> PP;
typedef long long ll;

const double EPS = 1e-8;
const int INF = 1e9;
const int MOD = 1e9+7;

int dy[] = {0,1,0,-1};
int dx[] = {1,0,-1,0};

int main(void) {
	int w,h;char c;
	cin >> w >> h >> c;
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			if( (i+j)%2==0)cout << c;
			else cout << (c=='B' ? "W" : "B");
		}
		cout << endl;
	}

	return 0;
}