#include<iostream>
using namespace std;
int main(){
	int w, h; char c;
	cin >> w >> h >> c;
	int q = ((c == 'B') ? 1 : 0);
	for (int y = 0; y < h; y++){
		for (int x = 0; x < w; x++){
			cout << ((q + y + x) % 2 ? 'B' : 'W');
		}
		cout << endl;
	}
	return 0;
}