#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int(i)=0;i<(n);i++)
int h,w;
string s[51];

bool a(int x,int y){
  bool f=0;
  if(x>0&&s[y].at(x-1)=='#') f=1;
  if(x<w-1&&s[y].at(x+1)=='#') f=1;
  if(y>0&&s[y-1].at(x)=='#') f=1;
  if(y<h-1&&s[y+1].at(x)=='#') f=1;
  return f;
}

int main(){
  cin>>h>>w;
  bool f=1;
  REP(i,h) cin>>s[i];
  REP(i,h) REP(j,w) if(s[i].at(j)=='#') f=f*a(j,i);
  cout<<(f?"Yes":"No");
}