using System;
using System.Numerics;
using System.Linq;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace debug
{
    class main
    {
        static void Main(string[] args)
        {
            //問題クラスを展開
            ProgramC a = new ProgramC();
            a.main();//実行する

        }

    }

    //ABC096
    class ProgramA
    {
        public void main()
        {
            //入力
            string[] s = Console.ReadLine().Split(' ');
            int a = int.Parse(s[0]);
            int b = int.Parse(s[1]);


            if (a<= b)
                Console.WriteLine(a);
            else
                Console.WriteLine(a-1);

        }
    }

    class ProgramB
    {
        public void main()
        {
            //入力
            string[] s = Console.ReadLine().Split(' ');

            int[] num = new int[3];

            for (int i = 0; i < 3; i++)
                num[i] = int.Parse(s[i]);

            Array.Sort(num);

            int k = int.Parse(Console.ReadLine());

            Console.WriteLine(num[0]+num[1]+num[2] * Math.Pow(2,k));
        }

        
    }

    class ProgramC
    {
        public void main()
        {

            //入力
            string[] s = Console.ReadLine().Split(' ');
            int h = int.Parse(s[0]);
            int w = int.Parse(s[1]);

            char[,] p = new char[w, h];

            for(int i = 0;i < h;i++)
            {
                string t = Console.ReadLine();
                for (int j = 0; j < w; j++)
                    p[j, i] = t[j];
            }

            for (int i = 0; i < h; i++)
                for (int j = 0; j < w; j++)
                {
                    if (p[j, i] == '.')
                        continue;

                    int count = 0;

                    if (i - 1 >= 0)
                        if (p[j, i - 1] == '#')
                            count++;

                    if (j - 1 >= 0)
                        if (p[j - 1, i] == '#')
                            count++;

                    if (j + 1 < w)
                        if (p[j + 1, i] == '#')
                            count++;

                    if (i + 1 < h)
                        if (p[j, i + 1] == '#')
                            count++;

                    if(count == 0)
                    {
                        Console.WriteLine("No");
                        return;
                    }
                }

            Console.WriteLine("Yes");

        }


    }



    class ProgramD
    {
        public void main()
        {

            //入力
            int n = int.Parse(Console.ReadLine());

            List<int> a = new List<int>(10000);

            for (int i = 0; i < 10000; i++)
                a.Add(i + 2);

            //10000までの素数を出す
            for(int i = 2;i <= Math.Sqrt(10000);i++)
            {
                List<int> t = new List<int>(10000);
                foreach (var s in a)
                {
                    if (s % i == 0 && s / i != 1)
                        t.Add(s);
                }

                foreach (var s in t)
                {
                    a.Remove(s);
                }


            }

            //5で割ったあまりが1だけのものを出す
            int count = 0;
            foreach (var s in a)
            {
                if (s % 5 == 1)
                {
                    Console.Write(s + " ");
                    count++;
                }

                if (count == n)
                    break;
            }
            
        }
    }

    


}






Measured memory_bytes: 27472