#include<bits/stdc++.h>
using namesapce std;

string s[52];

int main(void){
  int h, w;
  cin >> h >> w;
  for(int j=0;j<=w+1;j++) s[0] += '.';
  for(int i=0;i<h;i++){
    cin >> s[i];
    s[i] = '.' + s[i] + '.';
  }
  s[h+1] = s[0];
  
  int dx[4] = {1, 0, -1, 0};
  int dy[4] = {0, 1, 0, -1};
  for(int i=1;i<=h;i++)for(int j=1;j<=w;j++){
    if (s[i][j]=='#'){
      bool ok = false;
      for(int k=0;k<4;k++){
        if (s[i+dy[k]][j+dx[k]]=='#') {ok = true; break;}
      }
      if (!ok){
        cout << "No" << endl; return 0;
      }
    }    
  }
  cout << "Yes" << endl; return 0;
}  