using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using static System.Console;
using static System.Math;

namespace AtCodeeeer
{
    class AtCOOOOOOOOOOOder
    {
        static void Main(string[] args)
        {
            int[] s = ReadLine().Split(' ').Select(int.Parse).ToArray();
            int H = s[0];
            int W = s[1];
            string[,] glid = new string[H,W];
            for (int i = 0; i < H; i++)
            {
                string tmp = ReadLine();
                for (int j = 0; j < W; j++)
                {
                    glid[i, j] = tmp[j].ToString();
                }
            }

            string ans = "Yes";
            bool up = false;
            bool left = false;
            bool down = false;
            bool right = false;
            for (int i = 0; i < H; i++)
            {
                for (int j = 0; j < W; j++)
                {
                    if (glid[i,j] == "#")
                    {
                        //上を見れる場合
                        if (i - 1 >= 0)
                        {
                            if (glid[i - 1, j] == "#") up = true;
                        }
                        //左を見れる場合
                        if (j - 1 >= 0)
                        {
                            if (glid[i, j - 1] == "#") left = true;
                        }
                        //下
                        if (i + 1 < H)
                        {
                            if (glid[i + 1, j] == "#") down = true;
                        }
                        //右
                        if (j + 1 < W)
                        {
                            if (glid[i, j + 1] == "#") right = true;
                        }
                        if (!up && !left && !down && !right)
                        {
                            ans = "No";
                            break;
                        }
                    }
                    
                }
            }
            WriteLine(ans);
        }
    }
}
