#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  cin >> h >> w;
  char s[h + 5][w + 5];
  for (int i = 0; i <= h + 1; i++) {
    for (int j = 0; j <= w + 1; j++) {
      s[i][j] = '.';
    }
  }
  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][j] == '#') {
        if (s[i - 1][j] == '#' | s[i + 1][j] == '#' | s[i][j - 1] == '#' |
            s[i][j + 1] == '#') {
          continue;
        } else {
          cout << "No" << endl;
          return 0;
        }
      }
    }
    cout << "Yes" << endl;
    return 0;
  }
}
