#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char s[H][W];
  bool ans = true;
  for (int i = 1; i < H; i++) {
    for (int j = 1; j < W; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (s[i - 1][j] != '#' && s[i][j - 1] != '#' && s[i + 1][j] != '#' &&
          s[i][j + 1] != '#') {
        ans = false;
        break;
      }
    }
  }
  cout << (ans ? "Yes" : "No") << endl;
}
