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