#include<bits/stdc++.h>
using namespace std;

const long long INF = 1LL << 60;
#define MOD 1000000007;

typedef long long ll;

#define writeln(n) cout<<n<<endl;

typedef pair<float, float> P;

typedef pair<string, int> Psi;

int main() {

	int h, w;
	char c;
	cin >> w >> h >> c;

	char cc;
	if (c == 'B') {
		cc = 'W';
	} else {
		cc = 'B';
	}

	string s, ss;
	for (int i = 0; i < w; i++) {
		if (i % 2 == 0) {
			s += c;
			ss += cc;
		} else {
			if (c == 'B') {
				s += "W";

			} else {
				s += "B";
			}

			if (cc == 'B') {
				ss += "W";

			} else {
				ss += "B";
			}
		}

	}

	for (int i = 0; i < h; i++) {
		if(i %2==0){
			writeln(s);
		}else {
			writeln(ss);
		}
	}



}