#include <bits/stdc++.h>

using namespace std;

#define INF 1001000100010001000
#define MOD 1000000007
#define EPS 1e-10
#define int long long
#define rep(i, N) for (int i = 0; i < N; i++)
#define Rep(i, N) for (int i = 1; i < N; i++)
#define For(i, a, b) for (int i = (a); i < (b); i++)
#define pb push_back
#define eb emplece_back
#define mp make_pair
#define i_i pair<int, int>
#define vi vector<int>
#define vvi vector<vi >
#define vb vector<bool>
#define vvb vector<vb >
#define vp vector< i_i >
#define Edge pair< i_i, int>
#define all(a) (a).begin(), (a).end()
#define Int(x) int x; scanf("%lld", &x);
#define int2(x, y) int x, y; scanf("%lld %lld", &x, &y);
#define fir first
#define sec second
#define ffir first.first
#define fsec first.second
#define sfir second.first
#define ssec second.second
 
//int dxy[5] = {0, 1, 0, -1, 0};
// assign
 
signed main()
{
    int2(a, b);
    while (a) {
        a++; b++;
        vvi dp(a, vi(b, 0));
        Rep(i, a) {
            string st;
            cin >> st;
            rep(j, st.size()) {
                if (st[j] == '*') {
                    dp[i][j+1]++;
                }
            }
        }
        Rep(i, a) {
            Rep(j, b) {
                dp[i][j] += dp[i][j-1];
            }
        }
        Rep(j, b) {
            Rep(i, a) {
                dp[i][j] += dp[i-1][j];
            }
        } /*
        rep(i, a) {
            rep(j, b) {
                cout << dp[i][j] << " ";
            }
            cout << endl;
        } */

        int ans = 0;
        Rep(i, a) {
            Rep(j, b) {
                if (!dp[i][j]) {
                    ans = max(ans, i * j);
                }
            }
        }

        Rep(i, a) {
            Rep(j, b) {
                rep(k, i+1) {
                    rep(l, j+1) {
           //             cout << i << j << k << l << " ";
                        if (k == i && l == j) {
                            continue;
                        }
                        int tmp;
                        if (i == k || j == l) {
                            tmp = dp[i][j] - dp[k][l];
                        } else {
                            tmp = dp[i][j] - dp[i][l] - dp[k][j] + dp[k][l];
                        }
                        if (!tmp) {
            //                cout << (i - k) * (j - l) << endl;
                            ans = max(ans, (i - k) * (j - l));
                        }
                    }
                }
            }
        }
        cout << ans << endl;
        cin >> a >> b;
    }

    return 0;
}