#include <iostream>
#include <cstdlib>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
    int W, H; string C;
    cin >> W >> H >> C;
    for(int i = 0; i < H; i++){
        for(int j = 0; j < W; j++){
            if(C == "B"){
                if((i + j) % 2 == 0){
                    cout << "B";
                }else{
                    cout << "W";
                }
            }else if(C == "W"){
                if((i + j) % 2 == 0){
                    cout << "W";
                }else{
                    cout << "B";
                }
            }
        }
        cout << endl;
    }
    return 0;
}