import java.util.*;
import java.lang.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Scanner;

class Main
{
	public static char[][] arr = new char[1001][1001];
    public static int[][] vis = new int[1001][1001];
    boolean exist;
    public static int best, n, m;
    public static int nextI, nextJ;
    public static void dfs(int i, int j, int d)
    {

        if(i<0 || i>=m || j<0 || j>=n || arr[i][j]!='.') return;
	arr[i][j] = 'v';
	dfs(i+1, j, d+1);
	dfs(i, j+1, d+1);
	dfs(i, j-1, d+1);
	dfs(i-1, j, d+1);
	arr[i][j] = '.';
	if(d > best)
	{
		best = d;
                nextI=i;
                nextJ=j;

        }
    }

    public static int find()
{
	int maxlen = 0;
	if(arr[nextI][nextJ]!='.') return 0;
	while(true)
	{
		best = 0;
		dfs(nextI, nextJ, 0);
		if(best <= maxlen) break;
		else maxlen = best;
	}
	return maxlen;
}
	public static void main (String[] args) throws java.lang.Exception
	{
		int ile, d=0;

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        ile = Integer.parseInt(br.readLine());
        while(d<ile)
        {

            String line = br.readLine();
            n = Integer.parseInt(line.split(" ")[0]);
            m = Integer.parseInt(line.split(" ")[1]);
            //char[][] t = new char[m][n];
            String linia ;

            for(int i = 0; i<m; i++)
            {
                linia = br.readLine();
             for(int j = 0; j<n; j++)
             {
                    arr[i][j] = linia.charAt(j);

             }
            }


           nextI = nextJ = 0;
		for(int i=0; i<m; i++)
			for(int j=0; j<n; j++)
				if(arr[i][j]=='.')
				{
					nextI = i;
					nextJ = j;
					break;
				}
            System.out.println("Maximum rope length is " + find()+".");
            d++;
        }


	}
}