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

public class MainClass
{
	public const long Giri = 1000000007;

	public static void Main(string[] args)
	{
		var ps = Input().ToInt();
		var h = ps[0];
		var w = ps[1];
		var grid = new bool[w+4,h+4];
		for(int i = 0; i < h; i++)
		{
			var s = Console.ReadLine();
			for(int j = 0; j < w; j++)
			{
				grid[i+1, j+1] = s[j]=='#';
			}
		}
		
		for(int i = 1; i <= h; i++)
		{
			for(int j = 1; j <= w; j++)
			{
				if(!grid[i, j])
					continue;
					
				if(!(grid[i, j] && (grid[i, j+1] || grid[i+1, j] || grid[i-1, j] || grid[i, j-1])))
				{
					Console.WriteLine("No");
					return;
				}
			}
		}
		Console.WriteLine("Yes");
		
	}
	

	static long GCD(long a, long b)
	{
		var v = new[] { a, b };
		while (v[1] != 0) { v = new[] { v[1], v[0] % v[1] }; }
		return v[0];
	}
	public static string[] Input() { return Console.ReadLine().Split(' '); }
	public static int Clamp(int val, int max, int min = 0) { return Math.Min(max, Math.Max(min, val)); }
}

public static class Smarter
{
	public static int ToInt(this string str) { return int.Parse(str); }
	public static long ToLong(this string str) { return long.Parse(str); }
	public static int[] ToInt(this string[] str)
	{
		var r = new int[str.Length];
		for(int i = 0; i < str.Length; i++) r[i] = str[i].ToInt();
		return r;
	 }
}

