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

namespace AtCoder
{
    static class Program
    {
        static void Main()
        {
            //ここから

            var vs = IO.ReadLineToLongList();
            var H = vs[0];
            var W = vs[1];

            List<string> s = new List<string>();
            for(var i = 0; i < H; i++)
            {
                s.Add(IO.ReadLineToString());
            }

            string ans = "Yes";
            for(var i = 0; i < H; i++)
            {
                for(var j = 0; j < W; j++)
                {
                    if (s[i][j] == '#' && !Valid(H, W, i, j, s))
                    {
                        ans = "No";
                    }
                }
            }

            //ここまで

            Console.WriteLine(ans);
            Console.ReadKey();
        }

        static bool Valid(long H,long W, int i,int j,List<string> s)
        {

            if (i > 0)
            {
                if (s[i - 1][j] == '#') { return true; }
            }
            if (i < H - 1)
            {
                if(s[i+1][j] == '#') { return true; }
            }
            if (j > 0)
            {
                if (s[i][j - 1] == '#') { return true; }
            }
            if (j < W - 1)
            {
                if (s[i][j + 1] == '#') { return true; }
            }
            return false;
        }

    }

    static class Func
    {
        static public long mod = 1000000007;
        static public void Swap<T>(ref T a, ref T b) { T temp = a; a = b; b = temp; }
        static public long GCD(long a, long b) { return b != 0 ? GCD(b, a % b) : a; }
        static public long LCM(long a, long b) { return (long)a * b / GCD(a, b); }
        static public long Factorial(long a) { return a == 1 ? a : a * Factorial(a - 1); }


        public static double ToAngle(this double radian)
        {
            return (double)(radian * 180 / Math.PI);
        }

        public static double ToRadian(this double angle)
        {
            return (double)(angle * Math.PI / 180);
        }

        static public long Conbination(long n,long m)
        {
            if (m == 0) return 1;
            if (n == 0) return 0;
            return n * Conbination(n - 1, m - 1) / m;
        }

        static public void Factoring(long num, ref long[] vs)
        {
            if (num == 1)
            {
                vs[1]++;
            }
            for (long i = 2; i < Math.Sqrt(num); i++)
            {
                if (num % i == 0)
                {
                    vs[i]++;
                    Factoring(num / i, ref vs);
                }
            }
            vs[1]++;
        }
    }

    static class IO
    {
        static public string ReadLineToString() { return Console.ReadLine(); }
        static public long ReadLineToLong() { return long.Parse(Console.ReadLine()); }
        static public List<string> ReadLineToStringList() { return Console.ReadLine().Split(' ').ToList(); }
        static public List<long> ReadLineToLongList() { return Console.ReadLine().Split(' ').Select(long.Parse).ToList(); }

        static public List<double> ReadLineToDoubleList() { return Console.ReadLine().Split(' ').Select(double.Parse).ToList(); }

        static public void WriteStrings(object[] strings) { foreach (var o in strings) { Console.Write(o + " "); } }
    }
}

Measured memory_bytes: 13396