#include <bits/stdc++.h>
using namespace std;
int main(int argc, char* argv[]) {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int h, w;
  vector<string> s(h);
  for (int i = 0; i < (int)(h); i++) {
    cin >> s[i];
  }
  bool flag = true;
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (s[i][j] == '#')
        if (!((i + 1 < h and s[i + 1][j] == '#') ||
              (i - 1 < 0 and s[i - 1][j] == '#') ||
              (j + 1 < w and s[i][j + 1] == '#') ||
              (j + 1 < w and s[i][j + 1] == '#'))) {
          cout << "No\n";
          return 0;
        }
    }
  }
  cout << "Yes\n";
  return 0;
}
