#include <algorithm>

#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include <string>
#include <vector>
#include <deque>

using namespace std;

#define FORC(it, V) for(__typeof((V).begin()) it = (V).begin(); it != (V).end(); ++it)

typedef pair<int,int> point;
#define X first
#define Y second

const int MAXN = 101;

int R, S;
int ck;
int bio[MAXN][MAXN];
int bio2[MAXN][MAXN];
char grid[MAXN][MAXN+1];
char sol[MAXN][MAXN+1];

vector<point> P[2];
point dad[MAXN][MAXN];

const int dx[4] = { -1, 0, 1, 0 };
const int dy[4] = { 0, 1, 0, -1 };

inline int valid(int x, int y) { 
  if (x < 0 || y < 0 || x >= R || y >= S) return false;
  return true;
}

void fill(int x, int y)
{
  bio[x][y] = true;
  P[(x+y)%2].push_back(point(x,y));
  dad[x][y] = point(-1, -1);

  for (int pc = 0; pc < 4; ++pc) {
    int nx = x + dx[pc];
    int ny = y + dy[pc];

    if (!valid(nx, ny)) continue;
    if (grid[nx][ny] == 'X') continue;
    if (bio[nx][ny]) continue;

    fill(nx, ny);
  }
}

point sidro;

int match(int x, int y)
{
  if (x == -1) return true;
  if (bio2[x][y] == ck) return false;

  bio2[x][y] = ck;

  for (int pc = 0; pc < 4; ++pc) {
    int nx = x + dx[pc];
    int ny = y + dy[pc];
    if (!valid(nx, ny)) continue;
    if (grid[nx][ny] == 'X') continue;
    if (sidro.X == nx && sidro.Y == ny) continue;
    //    printf("nx = %d ny = %d\n", nx, ny);
    if (match(dad[nx][ny].X, dad[nx][ny].Y)) {
      dad[nx][ny] = point(x, y);
      return true;
    }
  }

  return false;
}

int main(void)
{
  for (; scanf("%d %d", &R, &S) == 2; ) {
    if (R+S == 0) break;

    for (int i = 0; i < R; ++i) {
      scanf("%s", grid[i]);
      strcpy(sol[i], grid[i]);
    }
    
    ck = 2;
    memset(bio, 0, sizeof bio);
    memset(bio2, 0, sizeof bio2);

    for (int x = 0; x < R; ++x)
      for (int y = 0; y < S; ++y) {
	if (grid[x][y] == 'X') continue;
	if (bio[x][y]) continue;

	P[0].clear(); P[1].clear();
	fill(x, y);

	for (int c = 0; c < 2; ++c) {
	  deque<point> Q;
	  int sum = 0;

	  FORC(it, P[c^1]) {
	    ++ck;
	    sidro = point(-2, -2);
	    int t = match(it->X, it->Y);
	    if (t == 0) {
	      Q.push_back(*it);
	    }
	    sum += t;
	  }

	  // 	  printf("c = %d prije sum = %d\n", c, sum);
	  // 	  for (int i = 0; i < R; ++i, putchar('\n'))
	  // 	    for (int j = 0; j < S; ++j)
	  // 	      printf("(%d,%d) ", dad[i][j].X, dad[i][j].Y);

	  FORC(it, P[c]) {
	    point s = dad[it->X][it->Y];
	    dad[it->X][it->Y] = point(-1, -1);

	    if (s.X != -1) {
	      Q.push_back(s);
	      --sum;
	    }

	    //	    printf("maknuo sum = %d\n", sum);
	    sidro = *it;

	    while (Q.size()) {
	      point ex = Q.front();
	      ++ck;
	      int t = match(ex.X, ex.Y);
	      //	      printf("matchao ex = (%d, %d)\n", ex.X, ex.Y);
	      //	      return (0-0);
	      if (t) {
		Q.pop_front();
		++sum;
	      } else {
		break;
	      }
	    }

	    //	    printf("sum = %d P = %d, %d\n", sum, P[0].size(), P[1].size());

	    if (sum == (int)P[c^1].size())
	      sol[it->X][it->Y] = 'B';
	    else
	      sol[it->X][it->Y] = 'A';
	  }
	}
      }

    for (int i = 0; i < R; ++i)
      puts(sol[i]);
    putchar('\n');
  }
  return 0;
}