using System;
using System.Collections.Generic;
using System.Linq;

class Progaram
{
    static int H, W;
    static bool[,] Visited;

    static void Dfs(int i, int j)
    {
        if (i == H || j == W || i == -1 || j == -1 || Visited[i, j] == true) return;
        Visited[i, j] = true;
        Dfs(i + 1, j);
        Dfs(i - 1, j);
        Dfs(i, j + 1);
        Dfs(i, j - 1);
    }

    static void Main(string[] args)
    {
        var l = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        H = l[0]; W = l[1];
        Visited = new bool[H, W];
        for (var i = 0; H > i; i++)
        {
            var ls = Console.ReadLine().ToCharArray();
            for (var j = 0; W > j; j++)
            {
                Visited[i, j] = ls[j] == '.';
            }
        }

        for (var i = 0; H > i; i++)
        {
            for (var j = 0; W > j; j++)
            {
                if (!Visited[i, j])
                {
                    Dfs(i, j);
                    foreach (var k in Visited)
                    {
                        if (!k)
                        {
                            Console.WriteLine("No");
                            return;
                        }
                    }
                    Console.WriteLine("Yes");
                    return;
                }
            }
        }
    }
}