#include <bits/stdc++.h>
using namespace std;
bool solve() {
  int H, W;
  vector<vector<bool>> v(H + 2, vector<bool>(W + 2, false));
  for (int i = 0; i < (int)(H); i++) {
    string s;
    cin >> s;
    for (int j = 0; j < (int)(W); j++) {
      v[i + 1][j + 1] = s[j] == '#';
    }
  }
  for (int i = 0; i < (int)(H); i++) {
    for (int j = 0; j < (int)(W); j++) {
      if (v[i + 1][j + 1]) {
        if (!(v[i][j + 1] || v[i + 2][j + 1] || v[i + 1][j] || v[i + 1][j + 2]))
          return false;
      }
    }
  }
  return true;
}
int main() {
  if (solve())
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
