#include <bits/stdc++.h>

#define LL long long
#define VI vector<int>
#define VVI vector<vector<int>>
#define VVVI vector<vector<vector<int>>>
#define VL vector<LL>
#define VVL vector<vector<LL>>
#define VVVL vector<vector<vector<LL>>>
#define VB vector<bool>
#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());
#define EPS 1e-14

template<class T> T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> void print(T x) { std::cout << x << std::endl; }

const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy = { 0, -1, 0, 1 }, dx = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）

using namespace std;


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    while (true) {
        int H, W;
        cin >> H >> W;
        if (H == 0 and W == 0) { break; }
        vector<string> field;
        FOR(i, 0, H) {
            string s;
            cin >> s;
            field.emplace_back(s);
        }

        VVI dp(H, VI(W, 0));
        FOR(x, 0, W) {
            FOR(y, 0, H) {
                if (y == 0) {
                    dp[y][x] = field[y][x] == '.' ? 1 : 0;
                    continue;
                }

                if (field[y][x] == '.') {
                    dp[y][x] = dp[y - 1][x] + 1;
                } else {
                    dp[y][x] = 0;
                }
            }
        }

        int ans = 0;
        FOR(y, 0, H) {
            FOR(x, 0, W) {
                int h = INT_MAX;
                FOR(w, 0, W - x) {
                    h = min(h, dp[y][x + w]);
                    ans = max(ans, h * (w + 1));
                }
            }
        }
        print(ans);
    }
}

