#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char> > square(h + 2, vector<char>(w + 2, '.'));
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> square[i][j];
    }
  }
  bool flag = true;
  vector<bool> direction(4, false);
  for (int i = 1; i <= h && flag; i++) {
    for (int j = 1; j <= w && flag; j++) {
      if (square[i][j] == '#') {
        if (square[i][j + 1] == '#') direction[0] = true;
        if (square[i][j - 1] == '#') direction[1] = true;
        if (square[i - 1][j] == '#') direction[2] = true;
        if (square[i + 1][j] == '#') direction[3] = true;
        if (direction[0] || direction[1] || direction[2] || direction[3]) {
          flag = true;
        } else {
          flag = false;
        }
      } else {
        continue;
      }
    }
  }
  if (flag) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
