#include <iostream>
#include <string>
using namespace std;

int main()
{
	int w, h;
	string c;
	cin >> w >> h >> c;

	bool k = c == "W";

	for (int i = 0; i < h; i++)
	{
		for (int j = 0; j < w; j++)
		{
			cout << "BW"[k];
			k ^= 1;
		}
		if (w % 2 == 0)
		{
			k ^= 1;
		}
		cout << endl;
	}
}