#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cctype>
#include <string>
#include <vector>
#include <list>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
using namespace std;

#define DEBUG(x) cout << '>' << #x << ':' << x << endl;
#define FOR(i, b) for (int i = 0; i < (b); ++i)
#define FOR2(i, a, b) for (int i = (a); i > (b); --i)
inline bool EQ(double a, double b) { return fabs(a-b) < 1e-9; }

const int INF = 1<<29;
typedef long long ll;

#define MAXN 111

int N,M,A,B;
char m[MAXN][MAXN],res[MAXN][MAXN];

bool get(int x,int y){
	if(x<0||y<0||x==N||y==M||m[x][y]!='.') return true;
	m[x][y]='#';
	bool res=!get(x-1,y)||!get(x+1,y)||!get(x,y-1)||!get(x,y+1);
	m[x][y]='.';
	return res;
}

int main() {
	int i,j;
	while(true){
		scanf("%d%d",&N,&M);
		if(N+M==0) break;
		FOR(i,N) scanf("%s",m[i]);
		FOR(i,N){
			FOR(j,M){
			if(m[i][j]=='.'){
				if(get(i,j)) res[i][j]='A';
				else res[i][j]='B';
			}
			else res[i][j]='X';
			}
			res[i][M]='\0';
		}
		FOR(i,N) printf("%s\n",res[i]);
		printf("\n");
	}
	return 0;
}