#define debug if(0)
#include<cstdio>
#include<stack>
#include<algorithm>
#include<cctype>
#include<vector>
#include<string>
using namespace std;

#define REP(i,n) for(int i = 0;i<(n);i++)
#define FOREACH(it,u) for(vector <int> ::iterator it = u.begin();it != u.end();it++)
#define PB push_back

typedef long long LL;

const int N = 10000;
char in[200][200];
int n1, n2;
vector<int> g[N];
int m1[N], m2[N];
bool c[N];

int blocked;

bool dfs(int u) {
	if(u<0) return true;
	if (c[u]) return false; else c[u]=true;
	FOREACH(v, g[u]) {
		if (*v == blocked)
			continue;
		if (dfs(m2[*v])) {m1[u]=*v;m2[*v] = u; return true; }
	}
	return false;
}

int matching() {
	REP(i,n1) m1[i]=-1;
	REP(i,n2) m2[i] = -1;
	bool changed;
	do {
		changed = 0;
		REP(i,n1) c[i]=false;
		REP(i,n1) if(i != blocked && m1[i]<0) changed |= dfs(i);
	} while(changed);
	int siz = 0;
	REP(i,n1) siz += (m1[i] !=-1);
	return siz;
}

void clear(int ilv) {
	REP(i,ilv) g[i].clear();
}

int dx[] = {-1,0,1,0};
int dy[] = {0,-1,0,1};

bool solve(){
	int n, m;
	scanf("%d %d", &n, &m);
	if (n == 0 && m == 0)
		return false;
	REP(i,n) {
		scanf("%s", in[i]);
	}
	blocked = -1;
	debug printf("n=%d, m=%d\n", n, m);
	n1 = n*m;
	n2 = n*m;
	REP(i,n) {
		REP(j,m) {
			if ((i+j)%2 == 0 && in[i][j]=='.') {
				REP(k,4) {
					int ni = i + dy[k];
					int nj = j + dx[k];
					if (ni < 0 || ni >= n || nj < 0 || nj >= m || in[ni][nj] == 'X')
						continue;
					debug printf("edge: %d -> %d\n", i*m+j, ni*m+nj);
					g[i*m+j].PB(ni * m + nj);
				}
			}
		}
	}
	int total = matching();
	debug printf("total=%d\n", total);
	REP(i,n) {
		REP(j,m) {
			if (in[i][j] == 'X') {
				printf("X");
				continue;
			}
			blocked = i*m+j;
			int res = matching();
			printf("%s", (res == total)?("B"):("A"));
		}
		printf("\n");
	}
	printf("\n");
	clear(n1);
	return true;
}

main(){
	while(1){
		if(!solve()) break;
	}
	return 0;
}