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

int main(){
    int n, m;
    char s;
    cin >> n >> m >> s;
    vector<vector<char>> l(m, vector<char>(n, ' '));
    for(int i = 0; i < m; i++){
        for(int j = 0; j < n; j++){
            if ((i + j) % 2 == 0) {
                l[i][j] = s;
            } else {
                l[i][j] = (s == 'B') ? 'W' : 'B';
            }
            cout << l[i][j];
        }
        cout << endl;
    }
}