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

int main(){
  int H, W;
  cin >> H >> W;
  vector<vector<char>> s(H, vector<char>(W));
  for(int i = 0; i < W; i++){
    for(int j = 0; j < H; j++){
      cin >> s.at(i).at(j);
    }
  }
  
  vector<int> dx = {0, -1, 1, 0};
  vector<int> dy = {1, 0, 0, -1};

  for(int i = 0; i < W; i++){
    for(int j = 0; j < H; j++){
      if(s.at(i).at(j)=='#'){
        int cnt = 0;
        for(int k = 0; k < 4; k++){
          int x = i + dx.at(k);
          int y = j + dy.at(k);
          //cout << x << y << endl;
          if(x==W or y==H)	continue;
          if(x<0 or y<0)	continue;
          if(s.at(x).at(y)=='#')	cnt++;
        }
        if(cnt==0){
          cout << "No" << endl;
          return;
        }
      }
    }
  }

  cout << "Yes"<< endl;
  return;
}