#include <iostream>
using namespace std;

int check(int,int);

int main(){
	int w,h;
	
	while(1){
	 cin>>w>>h;
	 if(w==0 && h==0){break;}
	 cout<<check(w,h)<<endl;
	}		
	return 0;
}

int check(int w,int h){
	char miyata[500][500];
	int x,y,cw,ch;
	int work,i;
	int max;
	
	for(y=0;y<h;y++){
	 for(x=0;x<w;x++){
	  cin>>miyata[x][y];
	 }
	}
	
	for(y=0;y<h;y++){
	 for(x=0;x<w;x++){
	  ch=0;work=y;while(work!=h && miyata[x][work]=='.'){ch++;work=y+ch;}
	  while(ch!=0){
	   cw=0;while(1){
		for(i=0;i<ch;i++){
		 if(miyata[x+cw][y+i]=='*'){break;}
		}
		if(i==ch){cw++;}else{break;}
	   }
	   work=cw*ch;
	   if(max<work){max=work;}
	   ch--;
	  }
	 }
	}
	
	return max;
}