#include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<vector>
#include<numeric>
using namespace std;
int main(){
  int h, w; cin >> h >> w;
  string s[51][51];

  for(int i = 0; i < h; i++){
    for(int j = 0; j < w; j++){
      cin >> s[h][w];
    }
  }

  bool ans = false;
  string ima = "Yes"

  for(int i = 0; i < h; i++){
    for(int j = 0; j < w; j++){

      if(s[i][j] == "#"){
        if(s[i-1][j] == "#" || s[i+1][j] == "#" || s[i][j + 1] == "#" || s[i][j-1] == "#"){
          continue;
        }
        else {
          ima = "No"
        }
      }

      else continue;
    }
  }

  cout << ima << endl;
}