#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>

using namespace std;

int main() {
	int w, h;
	char c;
	char mark[2] = {'B', 'B'};

	cin >> w >> h >> c;
	mark[c == 'B' ? 1 : 0] = 'W';

	for (int i = 0; i < h; i++) {
		for (int j = 0; j < w; j++) {
			cout << mark[(i + j) % 2];
		}
		cout << endl;
	}
	return 0;
}