#include <bits/stdc++.h>

using namespace std;

int main()
{
    int W, H; cin >> W >> H;
    char C; cin >> C;
    char s[2] = {'B', 'W'};
    for (int i = 0; i < H; ++i) {
        for (int j = 0; j < W; ++j) {
            printf("%c", s[((C == 'B') + i + j + 1) % 2]);
        }
        printf("\n");
    }
}