#include <iostream>
#include <cmath>
#include <cstring>
#include <string>
#include <set>
#include <algorithm>
#define ll long long
#define INF 0x3f3f3f3f
char g[110][110];
int vis[110][110];
using namespace std;
int main() {
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cin >> g[i][j];
			if(g[i][j] == '-')
				vis[i][j] = 1;
		}
	}
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			if(vis[i][j] == 1)
				continue;
			else {
				if(vis[i][j-1] != 2 && vis[i-1][j] != 2) {
					g[i][j] = 'B';
					vis[i][j] = 2;
				} else {
					g[i][j] = 'W';
					vis[i][j] = 3;
				}
			}
		}
	}
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cout << g[i][j];
		}
		cout << endl; 
	}
	return 0;
}