#include <iostream>

#include <vector>

#include <algorithm>

#include <string>

using namespace std;

int main(){

    int n,m;

    cin >> n >>m;

    vector<string> board(n,string(m,'B'));

    for(int i =  ; i < n; ++ i){

        for(int j =  ; j < m ; ++j){

            if(i%){

                if(j% == ) board[i][j] = 'W';

            }else{

                if(j%) board[i][j] ='W';

            }

        }

    }

    for(int i = ; i < n; ++ i){

        for(int j =  ; j < m; ++ j){

            char ch;

            cin >>ch;

            if(ch == '-') board[i][j] = '-';

            cout<<board[i][j];

        }

        cout<<endl;

    }

    cout<<endl;

}