#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <map>
#include <list>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <queue>
#include <iomanip>
#define INF 1050000000
#define SIZE 100001
#define MOD 1000000007

using namespace std;

int main(void)
{
	int w, h;
	string c;

	cin >> w >> h >> c;

	for (int i = 0; i < h; i++) {
		for (int j = 0; j < w; j++) {
			cout << c;
			if (c == "W")	   c = "B";
			else if (c == "B") c = "W"; 
		}
		cout << endl;
		if (w % 2 == 0) {
			if (c == "W")	   c = "B";
			else if (c == "B") c = "W";
		}
	}

	return (0);
}
/*for (int i = 0; i < n; i++) {

	}*/