#include <bits/stdc++.h>
#define rep(i, n) for (ll i = 0; i < n; ++i)
typedef long long ll;
using namespace std;
const int INF = 1e9;

int main() {
    int w, h;
    string s;
    cin >> w >> h >> s;

    int c = (s == "B");

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

    return 0;
}