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

int main() {
	int h, w;
	while(cin >> h >> w, h | w) {
		vector<string> in;
		for(int i = 0; i < h; i++) {
			string s;
			cin >> s;
			in.push_back(s);
		}
		vector<vector<int> > table = vector<vector<int> >(h, vector<int>(w, 0));

		for(int i = 0; i < in.size(); i++) {
			for(int j = 0; j < in[i].size(); j++) {
				if(in[i][j] == '.' && i == 0)
					table[i][j] = 1;
				else if(in[i][j] == '.')
					table[i][j] = table[i - 1][j] + 1;
				else
					table[i][j] = 0;
			}
		}

		int ret = 0;
		for(int i = 0; i < in.size(); i++) {
			for(int j = 0; j < in[i].size(); j++) {
				int minh = 1000;
				for(int k = j; k < in[i].size(); k++) {
					minh = min(minh, table[i][k]);
					ret = max(ret, minh * (k - j + 1));
				}
			}
		}

		cout << ret << endl;
	}
}