using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ABC096C
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] input = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            int h = input[0];
            int w = input[1];

            char[][] s = new char[h][];
            for(int i = 0; i < h; i++)
            {
                s[i] = Console.ReadLine().ToCharArray();
            }

            int[] dx = { 0, 1, 0, -1 };
            int[] dy = { 1, 0, -1, 0 };

            bool isYes = true;
            bool isFinished = false;
            for(int y = 0; y < h; y++)
            {
                for(int x = 0; x < w; x++)
                {
                    if (s[y][x] == '#')
                    {
                        bool isSharp = false;
                        for (int i = 0; i < 4; i++)
                        {
                            int nx = x + dx[i];
                            int ny = y + dy[i];

                            if (nx < 0 || w <= nx || ny < 0 || h <= ny)
                            {
                                continue;
                            }

                            if (s[nx][ny] == '#')
                            {
                                isSharp = true;
                                break;
                            }
                        }
                        if (!isSharp)
                        {
                            isYes = false;
                            isFinished = true;
                            break;
                        }
                    }
                }
                if (isFinished)
                {
                    break;
                }
            }

            if (isYes)
            {
                Console.WriteLine("Yes");
            }
            else
            {
                Console.WriteLine("No");
            }
        }
    }
}
