#include<iostream>
#include <bits/stdc++.h>
using namespace std;
int main()
{
   int h,w;
   cin >> h >> w ;
   char c[h][w] ;
  
  for(int i=0;i<h;i++){
     for(int j=0;j<w;j++){
       cin >> c[i][j] ;
     }   
   }
  
  bool ans true;
  
  for(int i=0;i<h;i++){
     for(int j=0;j<w;j++){
       if(c[i][j]=='#'){
         if(i!=0 && c[i-1][j]=='#')
           continue; //above
         else if(j!=0 && c[i][j-1]=='#')
           continue; //left
         else if(j!=(w-1) && c[i][j+1]=='#')
           continue ; //right
         else if(i!=(h-1) && c[i+1][j]=='#')
           continue ; //below
         else 
           ans = false ;
       }
     }   
   }
  
  if(ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  
    return 0;
}

