#include <bits/stdc++.h>
using namespace std;
#define forx(i,a,b) for(int i=(a);i<(b);i++)
#define rep(j,n) for(int j=0;j<(n);j++)

typedef long long ll; 

int main()
{ 
    int h,w;
    string ans="Yes";
    vector<vector<char>>s(55,vector<char>(55));
    
    rep(i,h)
    rep(j,w)
    cin>>s[i+1][j+1];
    
    forx(i,1,1+h)
    forx(j,1,1+w)
      if((s[i][j]=='#'&&s[i-1][j]!='#')   ||  (s[i][j]=="#"&&s[i+1][j]!='#')   ||   (s[i][j]=='#'&&s[i][j+1]!='#')   ||   (s[i][j]=='#'&&s[i][j-1]!='#')ans="No";
        
   cout<<ans<<endl;
return 0;
}
