using System;
using System.Linq;

namespace atcoder_Beginner_Contest096_Question3
{
    class Program
    {
        static void Main(string[] args)
        {
            bool possible = true;
            var input1 = Console.ReadLine().Split().Select(int.Parse).ToArray();
            char[][] paint = new char[input1[0]][];
            for (int i = 0; i < input1[1]; i++)
            {
                paint[i] = Console.ReadLine().ToCharArray();
            }

            for (int i = 0; i < input1[1]; i++)
            {
                for (int j = 0; j < input1[0]; j++)
                {
                    if (paint[i][j] == '.') continue;

                    if (j + 1 < input1[0] && paint[i][j + 1] != '#')
                        if (j - 1 >= 0 && paint[i][j - 1] != '#')
                            if (i + 1 < input1[1] && paint[i + 1][j] != '#')
                                if (i - 1 >=0 && paint[i - 1][j] != '#')
                                    possible = false;
                    if (!possible) break;
                }
                if (!possible) break;
            }

            Console.WriteLine(possible ? "Yes" : "No");
        }
    }
}
