#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<set>
#include<map>
#include<stack>
#include<complex>
#include<algorithm>
#include<string>
#include<vector>
#include<queue>
#include<deque>

using namespace std;
// using namespace __gnu_cxx;

typedef long long ll;
typedef double db;
typedef vector<int> vi;
typedef vector<string> vs;
typedef pair<int,int> pii;

#define INF (1<<30)
#define PB push_back
#define FI first
#define SE second
#define REP(i,n) for(int (i)=0;(i)<(n);++(i))
#define FUP(i,a,b) for(int (i)=(a);(i)<=(b);++(i))
#define FDN(i,a,b) for(int (i)=(a);(i)>=(b);--(i))

struct Pnt{
    char c;
    int id,rea;
    char win;
};

int n,e;
const int zX[4] = {-1, 0, 1, 0};
const int zY[4] = {0, 1, 0, -1};

inline bool ok(int x, int y){
    return (x >= 0 && x < n && y >= 0 && y < e);
}

Pnt tab[103][103];

int ID;
int sklsize[20000];
int exam1x[20000];
int exam1y[20000];
int exam2x[20000];
int exam2y[20000];

int stosX[20000];
int stosY[20000];
int ww;

void czysc(){
    REP(i,ww){
        tab[stosX[i]][stosY[i]].id = tab[stosX[i]][stosY[i]].rea;
    }
    ww=0;
}

void skladowe(int a, int b){
    tab[a][b].id = ID;
    sklsize[ID]++;
    if(exam1x[ID] == -1){ exam1x[ID] = a; exam1y[ID] = b; }
    else if(exam2x[ID] == -1){ exam2x[ID] = a; exam2y[ID] = b; }
    REP(i,4){
        int xx = a + zX[i];
        int yy = b + zY[i];
        if(ok(xx, yy) && tab[xx][yy].id == -1){
            skladowe(xx, yy);
        }
    }
}

bool win(int a, int b){
    //cout << "WIN " << a << " " << b << endl;
    tab[a][b].rea = tab[a][b].id;
    stosX[ww] = a;
    stosY[ww] = b;
    ww++;
    tab[a][b].id = -1;
    REP(i,4){
        int xx = a + zX[i];
        int yy = b + zY[i];
        if(ok(xx, yy) && tab[xx][yy].id >= 0){
            if(!win(xx,yy))
                return true;
        }
    }
    return false;
}

void mark(int a, int b, bool rozne, bool jaki, int iid){
    tab[a][b].win = jaki;
    tab[a][b].id = -1;
    REP(i,4){
        int xx = a + zX[i];
        int yy = b + zY[i];
        if(ok(xx, yy) && tab[xx][yy].id == iid){
            bool nowy = jaki;
            if(rozne) nowy = !nowy;
            mark(xx,yy,rozne, nowy, iid);
        }
    }
}

int main(){
    while(true){
        char c;
        scanf("%d%d", &n, &e);
        do c = getchar(); while(c!='\n');
        if(n==0 && e==0) break;
        REP(i,n){
            REP(j,e){
                tab[i][j].c = getchar();
                if(tab[i][j].c == '.')
                    tab[i][j].id = -1;
                else
                    tab[i][j].id = -10;
            }
            do c = getchar(); while(c!='\n');
        }
        
        // skladowe
        ID = 0;
        exam1x[ID] = exam1y[ID] = exam2x[ID] = exam2y[ID]  = -1;
        sklsize[ID] = 0;
        REP(i,n) REP(j,e){
            if(tab[i][j].id == -1){
                skladowe(i,j);
                ID++;
                exam1x[ID] = exam1y[ID] = exam2x[ID] = exam2y[ID]  = -1;
                sklsize[ID] = 0;
            }
        }

        // dla kazdej skladowej dwa sasiednie pola
        REP(i,ID){
            int x = exam1x[i];
            int y = exam1y[i];
            int xx,yy;
            tab[x][y].win = win(x,y);
            czysc();
            if(sklsize[i] > 1){
                xx = exam2x[i];
                yy = exam2y[i];
                tab[xx][yy].win = win(xx,yy);
                czysc();
                bool rozne = (tab[x][y].win != tab[xx][yy].win);
                /*if(rozne) cout << "ROZNE" << endl;
                else cout << "NIE" << endl;*/
                mark(x,y,rozne,tab[x][y].win, tab[x][y].id);
            }
        }
        REP(i,n){
            REP(j,e){
                char cc = tab[i][j].c;
                if(cc == 'X'){
                    putchar('X');
                } else if(tab[i][j].win){
                    putchar('A');
                } else {
                    putchar('B');
                }
            }
            putchar('\n');
        }
        putchar('\n');
    }
    return 0;
}