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