using System;
class Program
{
	static void Main()
  {
	string[] input = Console.ReadLine().Split(' ');
	int h = int.Parse(input[0]);
	int w = int.Parse(input[1]);
    string[] masu = new string[h];//入力マスを受け取る
    int result = 1;
	for(int i = 0; i < h; i++)
        {
          masu[i] = Console.ReadLine();	
        }
      
       
        for(int i = 0; i < h; i++)
        {
          for(int j = 0; j < w; j++)
          {
          	if(masu[i][j] == '#')
            {
              result = 0;
            if(i-1 >= 0)
            {
              if(masu[i-1][j] == '#')result = 1;
            }
               if(i+1<h)
            {
              if(masu[i+1][j] == '#')result = 1;
            }
               if(j-1 >= 0)
            {
              if(masu[i][j-1] == '#')result = 1;
            }
               if(j+1<w)
            {
              if(masu[i][j+1] == '#')result = 1;
            }

            }
                  
                
       	  }
          
          
        }
      Console.WriteLine((result == 1) ? "Yes" : "No");
  }
  
}