#include <bits/stdc++.h>
using namespace std;
int main() {
  char a[50][50];
  int h, w, f = 0;
  cin >> h >> w;
  for (int i = 0; i < (h); ++i) {
    for (int j = 0; j < (w); ++j) {
      cin >> a[i][j];
    }
  }
  for (int i = 0; i < (h); ++i) {
    for (int j = 0; j < (w); ++j) {
      if (a[i][j] = '#' && a[i + 1][j] == '.' && a[i - 1][j] == '.' &&
                    a[i][j + 1] == '.' && a[i][j - 1] == '.') {
        f++;
      }
    }
  }
  if (f == 1)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
}
