#include "bits/stdc++.h"
using namespace std;
using Graph = vector<vector<int>>;
typedef long long ll;
typedef pair<ll, ll> P;
#define rep(i,n) for (ll i = 0; i < (n); ++i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const long long mod = 1e9 + 7;

ll gcd(ll a, ll b) {
	return b ? gcd(b, a % b) : a;
}

ll lcm(ll a, ll b) {
	return a / gcd(a, b) * b;
}

int main() {
	ll h, w;
	char c;
	cin >> h >> w >> c;
	
	rep(i, w) {
		rep(j, h) {
			if (c == 'B') {
				if ((i + j) % 2 == 0) {
					cout << "B";
				} else {
					cout << "W";
				}
			} else {
				if ((i + j) % 2 == 0) {
					cout << "W";
				} else {
					cout << "B";
				}
			}
		}
		cout << endl;
	}

}