#include<iostream>
#include<vector>
#include<algorithm>
#include<map>
#include<bitset>
#include<cmath>
#include<queue>
typedef long long ll;
using namespace std;
typedef pair<int, int>pii;
void speed()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
}
int xx[4] = { 0,0,-1,1 };
int yy[4] = { 1,-1,0,0 };
int n, m;
int tsum;
bool a[1005][1005];
bool vis[1005][1005];
pii que[1005];
bool check(int x, int y)
{
    if (x <= n && x >= 1 && y <= m && y >= 1&&a[x][y])
        return 1;
    else
        return 0;
}
void dfs(int x, int y)
{
    if (vis[x][y]) return;
    vis[x][y] = 1;
    que[++tsum] = { x,y };
    for (int i = 0; i < 4; i++)
    {
        if (check(xx[i] + x, yy[i] + y)&&!vis[xx[i]+x][yy[i]+y])
        {
            dfs(xx[i] + x, yy[i] + y);
        }
    }
}
int main()
{
    speed();
    int t;
    cin >> t;
    while (t--)
    {

        cin >> n >> m;
        for (int i = 1; i <= n; i++)
        {
            string s;
            cin >> s;
            for (int j = 1; j <= m; j++)
            {
                if (s[j - 1] == '.')
                    a[i][j] = 1;
            }
        }
        int ans = 0;
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= m; j++)
            {
                tsum = 0;
                if (!vis[i][j]&&a[i][j])
                {
                    dfs(i, j);
                    bool tis = 1;
                    for (int k = 1; k <= n; k++)
                    {
                        for (int l = 1; l <= m; l++)
                        {
                            if (!tis)
                                break;
                            if (i == k && j == l) continue;
                            int disx = k - i;
                            int disy = l - j;
                            int is = 0;
                            for (int o = 1; o <= tsum; o++)
                            {
                                if (!a[que[o].first + disx ][que[o].second + disy])
                                {
                                    is = 1;
                                    break;
                                }
                            }
                            if (!is)
                            {
                                tis = 0;
                            }
                        }
                    }
                    if (tis)
                    {
                        ans = max(ans,tsum);
                    }
                }
            }
        }
        cout << ans << '\n';
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= m; j++)
            {
                vis[i][j] = 0;
                a[i][j] = 0;
            }
        }
    }
    return 0;
}