#include <bits/stdc++.h>
#define For(i, a, b) for(long long i = a; i < b; i++)
#define rep(i, n) For(i, 0, n)
#define rFor(i, a, b) for(long long i = a; i >= b; i--)
#define ALL(v) (v).begin(), (v).end()
#define rALL(v) (v).rbegin(), (v).rend()
using namespace std;

using lint = long long;
using ld = long double;

int main() {
    int w, h;
    char c;
    cin >> w >> h >> c;
    vector<vector<char>> ans(h, vector<char>(w));
    rep(i, h) {
        rep(j, w) {
            if (j == 0) {
                if (i == 0) {
                    ans[i][j] = c;
                } else {
                    ans[i][j] = (ans[i - 1][j] == 'B' ? 'W' : 'B');
                }
            } else {
                ans[i][j] = (ans[i][j - 1] == 'B' ? 'W' : 'B');
            }
        }
    }
    rep(i, h) {
        rep(j, w) {
            cout << ans[i][j];
        }
        cout << endl;
    }
}