#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main(){
	int h, w;
	while(cin >> h >> w, h+w){
		vector<string> v(h);
		for(int i=0; i< h; i++) cin >> v[i];

		int ret = 0;
		for(int i=0; i < v.size(); i++)for(int j=0; j< v[0].size(); j++)if(v[i][j] != '*'){
			int x = i, y = j;
			while(y+1 < w && v[x][y+1] != '*') y++;
			ret = max(ret, (x-i+1)*(y-j+1));
			while(x+1 < h){
				int c = -100;
				for(int k=j; k <= y; k++) if(v[x+1][k] == '*'){c = k-1; break;}
				if(j <= c || c == -100){
					x++;
					if(c != -100) y = c;
					ret = max(ret, (x-i+1)*(y-j+1));
				}
				else break;
			}
		}
		cout << ret << endl;
	}
}