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

namespace Painting_problem
{
    class Program
    {
        static int height = 0;
        static int width = 0;
        static int[,] datas = new int[height + 1, width + 1];
        static void Main(string[] args)
        {
            String input = Console.ReadLine();
            try
            {
                height = Int32.Parse(input.Split(' ')[0]);
                width = Int32.Parse(input.Split(' ')[1]);
            
                for (int i = 0; i < height; i++)
                {
                    input = Console.ReadLine();
                    for (int j = 0; j < width; j++)
                    {
                        if (input[j].Equals('#'))
                        {
                            datas[i, j] = 1;
                        }
                    }
                }
            }
            catch (Exception)
            {
                Console.WriteLine("形式エラー");
                Console.ReadLine();
                return;
            }
            //Paint
            for (int i = 0; i < height; i++)
            {
                for (int j = 0; j < width; j++)
                {
                    if (!PaintOut(i, j))
                    {
                        Console.WriteLine("No");
                        return;
                    }
                }
            }
            Console.WriteLine("Yes");
        }

        static Boolean PaintOut(int x, int y)
        {
            if (datas[x,y] == 1)
            {
                bool isSuccess = false;
                if (x > 0)
                {
                    isSuccess = isSuccess || datas[x - 1, y] != 0;
                }
                if (y > 0)
                {
                    isSuccess = isSuccess || datas[x, y - 1] != 0;
                }
                isSuccess = isSuccess || datas[x + 1, y] != 0;
                isSuccess = isSuccess || datas[x, y + 1] != 0;
                return isSuccess;
            }
            return true;
        }
    }
}
