#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<int>> M(H + 2, vector<int>(W + 2, 0));
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      char c;
      cin >> c;
      if (c == '#')
        M[i][j] = 1;
      else
        M[i][j] = 0;
    }
  }
  bool ans = true;
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (M[i][j] == 1) {
        if (M[i - 1][j] + M[i + 1][j] + M[i][j - 1] + M[i][j + 1] == 0)
          ans = false;
        break;
      }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
