#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string ans = "Yes";
  vector<vector<char>> s(55, vector<char>(55));
  for (int i = 0; i < (h); i++)
    for (int j = 0; j < (w); j++) cin >> s[i + 1][j + 1];
  for (int i = (1); i < (1 + h); i++)
    for (int j = (1); j < (1 + w); j++)
      if (s[i][j] == '#' && s[i - 1][j] != '#' && s[i + 1][j] != '#' &&
          s[i][j + 1] != '#' && s[i][j - 1] != '#')
        ans = "No";
  cout << ans << endl;
  return 0;
}
