#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

int main() {
    int w, h; cin >> w >> h;
    char c; cin >> c;
    vector<string> s(h, string(w, 'B'));
    for (int i = 0; i < h; i++) for (int j = 0; j < w; j++) {
        if ((i + j) % 2 ^ (c == 'W')) s[i][j] = 'W';
    }
    for (auto &x: s) cout << x << endl;
    return 0;
}