#include <iostream>
#include <string>
using namespace std;
int main() {
	int i,j,w,h;
	string c,s;
	cin >> w >> h >> c;
	string arr[h][w];
	s = (c=="B") ? "W" : "B";
	for (i = 0; i < h; i++) {
		for (j = 0; j < w; j++) {
			if ((i + j) % 2 == 0) {
				arr[i][j] = c;
			}else {
				arr[i][j] = s;
			}
			if (j == w - 1) {
				cout << arr[i][j] << "\n";
			}else{
				cout << arr[i][j];
			}
		}
	}
}