#include <cstdio>
#include <algorithm>

using namespace std;

int main(void) {
    int h, w;
    while (true) {
        scanf("%d%d", &h, &w);
        if (h == 0 || w == 0) break;
        char g[w][h];
        int t[w][h];
        for (int j = 0; j < h; j++) {
            for (int i = 0; i < w; i++) {
                scanf(" %c", &g[i][j]);
            }
        }
        for (int i = 0; i < w; i++) {
            for (int j = 0; j < h; j++) {
                int c = 0;
                for (int k = i; k < w; k++) {
                    if (g[k][j] == '.') {
                        c++;
                    } else {
                        break;
                    }
                }
                t[i][j] = c;
            }
        }
        int max_s = 0;
        for (int i = 0; i < w; i++) {
            for (int j = 0; j < h; j++) {
                int min_t = t[i][j];
                for (int k = j; k < h; k++) {
                    if (t[i][j] == 0) break;
                    min_t = min(min_t, t[i][k]);
                    max_s = max(max_s, min_t * (k - j + 1));
                }
            }
        }
        printf("%d\n", max_s);
    }
    return 0;
}