#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

int main(){
  int h,w;

  while(1){
    cin >> h >> w;
    if(!h && !w)break;
    
    vector<string> grid;
    for(int i=0;i<h;i++){
      string tmp;
      cin >> tmp;
      grid.push_back(tmp);
    }

    int ans = 0;
    for(int i=0;i<h;i++){
      for(int j=0;j<w;j++){
	if(grid[i][j] == '.'){
	  int x = w;
	  int tmp = 0;
	  for(int k=i;k<h;k++){
	    if(grid[k][j]=='*')break;
	    int l;
	    for(l=j;l<w;l++){
	      if(grid[k][l]=='*'){
		x = min(x,l);
		break;
	      }
	    }
	    tmp = max(tmp,(x-j)*(k-i+1));
	  }
	  ans = max(ans,tmp);
	}
      }
    }
    cout << ans << endl;
  }
}