#include <bits/stdc++.h>
using namespace std;
                                                                                                
  
int main(){
                                                                     

    int h, w, i, j;

    int sw = 0;

    cin >> h >> w;

    char s[h + 1][w + 1];



    for( i = 1 ; i <= h ; i = i + 1 ){

         for( j = 1 ; j <= w ; j = j + 1 ){

              cin >> s[i][j];

              if( s[i][j] == '#') sw = 1;

              }

         }


    if( sw != )

    for( i = 1 ; i <= h ; i = i + 1 ){

         for( j = 1 ; j <= w ; j = j + 1 ){

              if( s[i][j] == '#' ){

                  if( s[i][j + 1] == '#' || s[i + 1][j] == '#' || s[i][j - 1] == '#' || s[i - 1][j] == '#' ) i = i;

                  else{

                         cout << "No" << endl;

                         return 0;

                         }

                  }

              }

         }

    if(  )

    cout << "Yes" << endl;


    return 0;

    }