#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main(void){
  int H,W;
  cin >> H >> W;
  
  vector<vector<char>>grid(H + 2,vector<char>(W + 2,'p'));
  
  for(int i=1;i<=H;i++){
    for(int j=0;j<=W;j++;)
    cin >> grid[i][j];
  }
  
  bool ans = true;
  
  for(int i=1;i<=H;i++){
    for(int j=1;j<=W;j++){
      if(grid[i][j] == '#'){
        if(grid[i - 1][j] != '#' && grid[i + 1][j] != '#' && grid[i][j - 1] != '#' && grid[i][j + 1] != '#')
          ans = false;
      }
    }
  }
  
  if(ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  
  return 0;
}