#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char m[66][66];
  for (int i = i; i <= h; i++) {
    for (int j = i; j <= w; j++) {
      cin >> m[i][j];
    }
  }
  string ans = "Yes";
  for (int i = i; i <= h; i++) {
    for (int j = i; j <= w; j++) {
      if (m[i][j] == '#' && m[i + 1][j] != '#' && m[i - 1][j] != '#' &&
          m[i][j + 1] != '#' && m[i][j - 1] != '#')
        ans = "No";
    }
  }
  cout << ans << endl;
}
