#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cassert>
#include <iostream>
#include <cctype>
#include <sstream>
#include <string>
#include <list>
#include <vector>
#include <queue>
#include <set>
#include <stack>
#include <map>
#include <utility>
#include <numeric>
#include <algorithm>
#include <iterator>
#include <bitset>
#include <complex>
#include <fstream>
#include <iomanip>
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
typedef vector<int> vint;
typedef pair<int, int> pint;
#define rep(i, n) REP(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define MSG(a) cout << #a << " " << a << endl;
#define REP(i, x, n) for(int i = x; i < n; i++)
template<class T, class C> void chmax(T& a, C b){ if(a < b) a = b; }
template<class T, class C> void chmin(T& a, C b){ if(b < a) a = b; }
template<class T, class C> pair<T, C> mp(T a, C b){ return make_pair(a, b); }

int main()
{
	int H, W;
	while(cin >> H >> W && H)
	{
		vector<string>	field(H);
		vector<vint>	dp(H, vint(W, 0));

		rep(i, H) cin >> field[i];
        
        rep(y, H) rep(x, W)
            for(int dx = 0; x + dx < W && field[y][x + dx] == '.'; dx++)
                dp[y][x]++;
        
		int res = 0;
        rep(y, H) rep(x, W)
		{
			int mi = 1 << 30;
			rep(k, y + 1)
        	{
				chmin(mi, dp[y - k][x]);
				chmax(res, mi * (k + 1));
        	}
		}
		
		cout << res << endl;
    }
}