#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max
#include <string>	//string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap
#include <cstdlib>	//abs(int)
#include <sstream>	//stringstream,getline

using namespace std;

int main() {

	int W, H;
	string C;
	cin >> W >> H >> C;

	string temp = "BW";
	bool flg;
	if (C != "B") {
		flg = true;
	}
	else {
		flg = false;
	}

	for (int i = 0; i < H; i++) {
		for (int j = 0; j < W; j++) {
			cout << temp[flg];
			flg = !flg;
		}
		cout << endl;
		if (W % 2 == 0) {
			flg = !flg;
		}
	}

	return 0;

}