#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  cin >> h >> w;
  vector<vector<char> > s;
  vector<char> kari;
  for (int i = 0; i < w + 2; i++) {
    kari.push_back('.');
  }
  s.push_back(kari);
  for (int i = 0; i < h; i++) {
    vector<char> gyou;
    gyou.push_back('.');
    for (int j = 0; i < w; j++) {
      char ness;
      cin >> ness;
      gyou.push_back(ness);
    }
    gyou.push_back('.');
    s.push_back(gyou);
  }
  s.push_back(kari);
  bool able = true;
  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 + 1][j] == '.' && s[i][j - 1] == '.' &&
            s[i][j + 1] == '.') {
          able = false;
        }
      }
    }
  }
  if (able) {
    cout << "Yes";
  } else {
    cout << "No";
  }
  return 0;
}
