#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string ans = "Yes";
  vector<vector<char>> s(52, vector<char>(52));
  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 < (53); i++)
    for (int j = (1); j < (53); j++)
      if (s[i][j] == '#') {
        if (s[i][j + 1] == '#') continue;
        if (s[i][j - 1] == '#') continue;
        if (s[i + 1][j] == '#') continue;
        if (s[i - 1][j] == '#') continue;
        ans == "No";
        break;
      }
  cout << ans << endl;
  return 0;
}
