#include<bits/stdc++.h>

using namespace std;
int main(){
  int h, w;
  cin >> h >> w;

  char field[h][w];
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin >> field[i][j];
    }
  }

  int can=0;
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      if(field[i][j]=='#'){
	      can=0;
	      if((i-1>0)&&(field[i-1][j]=='#'))can=2;
	      else if((i+1<h)&&(field[i+1][j]=='#'))can=2;
	      else if((j-1>0)&&(field[i][j-1]=='#'))can=2;
	      else if((j+1<w)&&(field[i][j+1]=='#'))can=2;
      }
    }
    if(can==0)break;
  }

  if(can==0)cout << "No" << endl;
  else cout << "Yes"s << endl;

}
