#include <bits/stdc++.h>
using namespace std;

constexpr int INF = 1e9;

int main() {
    int H, W;
    while(cin >> H >> W, H) {
        vector<string> v(H);
        for(int i=0; i<H; ++i) {
            cin >> v[i];
        }
        vector<vector<int>> sum(H, vector<int>(W+1));
        for(int i=0; i<H; ++i) {
            for(int j=W-1; j>=0; --j) {
                if(v[i][j] == '.') {
                    sum[i][j] = sum[i][j+1] + 1;
                }
            }
        }
        int res = 0;
        for(int i=0; i<H; ++i) {
            for(int j=0; j<W; ++j) {
                int mi = INF;
                for(int k=0; k+i<H; ++k) {
                    mi = min(mi, sum[i+k][j]);
                    res = max(res, (k+1)*mi);
                }
            }
        }
        cout << res << endl;
    }
}
