#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
int main() {
	int w,h;
	string c;
	cin >> w >> h >> c;
	bool b = false;
	if(c == "B") b = true;
	bool tmp = !b;

	REP(i,h){
		if(b == tmp) b = !b;
		tmp = b;
		REP(i,w){
			if(b) cout << "B";
			else cout << "W";
			b = !b;
		}
		cout << endl;
	}
	return 0;
}