#include <iostream>
using namespace std;

int main(){
    int w,h;
    char c;
    cin >> w >> h >> c;
    for(int i = 0; i < h; ++i){
        for(int j = 0; j < w; ++j){
            if(c == 'W'){
                 if(j%2==0){
                    cout << "W";
                }else{
                    cout << "B";
                }
            }else if(c == 'B'){
                if(j%2==0){
                    cout << "B";
                }else{
                    cout << "W";
                }
            }
        }
        cout << "\n";
    }
    return 0;
}