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

int main() {
    int W, H;
    char C;
    cin >> W >> H >> C;

    for (int h = 0; h < H; h++) {
        for (int w = 0; w < W; w++) {
            cout << ((h + w) & 1 ? char('W' - C + 'B') : C);
        }
        cout << endl;
    }
}