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

int main() {

  int h,w;
  cin >> h >> w;
  
  vector<vector<char>> s(h+2,vector<char> (w+2,'.'));
  
  for ( int i = 1; i < h+1; i++){
    for ( int j = 1; j < w+1; j++){
      cin >> s[i][j];
    }
  }
  
  for ( int i = 1; i < h+1; i++){
    for ( int j = 1; j < w+1; j++){
      if ( s[i][j] == '#' ){
        if ( s[i-1][j] == '#' ||
             s[i][j-1] == '#' ||
             s[i][j+1] == '#' ||
             s[i+1][j] == '#' ){
          continue;
        }else{
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  
  cout << "Yes" << endl;  
  
}

#include <bits/stdc++.h>
 
int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(0); std::cout.tie(0);
 
    std::string s;
    std::getline(std::cin, s);
    std::vector<bool> dict(26, false);
    for (char c : s)
        dict[c - 'a'] = true;
    std::string r = "None";
    for (std::size_t i = 0; i < dict.size(); ++i) {
        if (!dict[i]) {
            r = i + 'a';
            break;
        }
    }
    std::cout << r << std::endl;
 
    return 0;
}