using System;
class Program{
  private char[][] c;
  static bool Check(int i,int j){
    bool f = false;
    try{f=f||c[i-1][j]=='#';}catch{}
    try{f=f||c[i+1][j]=='#';}catch{}
    try{f=f||c[i][j-1]=='#';}catch{}
    try{f=f||c[i][j+1]=='#';}catch{}
    return f;
  }
  static void Main(){
    string[] s = Console.ReadLine().Split(' ');
    int h=int.Parse(s[0]), w=int.Parse(s[1]);
    c = new char[h][];
    for (int i=0;i<h;i++)
      c[i]=Console.ReadLine().ToCharArray();
    bool ans=true;
    for (int i=0;i<h;i++){
      for (int j=0;j<w;j++){
        if (c[i][j]=='#'){
          ans = ans && Check(i,j);
        }
      }
    }
    Console.WriteLine(ans ? "Yes" : "No");
  }
}