#include <cstdio>
#include <iostream>
#include <string>
using namespace std;

string field[505];
int H;
int W;

void input() {
  for (int i=0; i<H; i++) {
    cin >> field[i];
  }
}

void output() {
  for (int i=0; i<H; i++) {
    cout << field[i] << endl;
  }
}

int main() {
  while(scanf("%d %d", &H, &W),H||W) {
    input();

    int max_area = 0;
    // ???????????????
    for (int i=0; i<H; i++) {
      for (int j=0; j<W; j++) {
	int rightest = W;
	int k, l;
	for (k=i; k<H; k++) {
	  if (field[k][j] == '*') {
	    break;
	  }
	  
	  for (l=j; l<rightest; l++) {
	    if (field[k][l] == '*') {
	      rightest = l;
	      break;
	    }
	  }
	  int tmp_area = (k-i+1)*(l-j);
	  // printf("i:%d j:%d k:%d l:%d tmp_area:%d\n", i, j,k,l, tmp_area);
	  if (max_area < tmp_area) {
	    max_area = tmp_area;
	  }
	}
	// printf("i%d j%d max_area%d\n", i,j,max_area);
      }
    }
    printf("%d\n", max_area);
  }
}