#include <iostream>
#include <map>
using namespace std;

int main() {
    int w, h;
    char c;
    cin >> w >> h >> c;

    map<int, char> map;
    map[0] = c;
    if (c == 'B') map[1] = 'W';
    else map[1] = 'B';

    for (int r = 0; r < h; r++) {
        for (int c = 0; c < w; c++) {
            char color = map[(r + c) % 2];
            cout << color;
        }
        cout << endl;
    }
    return 0;
}