//何故かRE

#include <bits/stdc++.h>
using namespace std;
int h,w,i,j;
char s[50][50];
int main(){
  cin>>h>>w;
  for(i=0;i<h;i++){
    for(j=0;j<w;j++){
      cin>>s[i][j];
    }
  }
  int cou=0;
  for(i=0;i<h;i++){
    for(j=0;j<w;j++){
      if(s[i][j]=='#'&&s[i-1][j]!='#'&&s[i+1][j]!='#'&&s[i][j-1]!='#'&&s[i][j+1]!='#'){
      cou++;
      }
    }
  }
  if(cou!=0)cout<<"No"<<endl;
  else cout<<"Yes"<<endl;
  return 0;
}
