#include "iostream"
#include "algorithm"
using namespace std;

int main() {
    int a, b;
    string c;
    string w="WB";

    cin >> a >> b >> c;
    if (c == "B") {
        w="BW";
    }
    for (int l = 0; l < b; ++l) {
        for (int m = 0; m < a; ++m) {
            cout<<w[(l+m)%2];
        }
        cout<<endl;
    }
    return 0;
}