#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string s[51][51];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[h][w];
    }
  }
  bool ans = false;
  string ima = "Yes";
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == "#") {
        if (i == 0 || j == 0) {
          if (s[i][j + 1] != "#" && s[i + 1][j] != "#") ima = "No";
        } else if (s[i - 1][j] == "#" || s[i + 1][j] == "#" ||
                   s[i][j + 1] == "#" || s[i][j - 1] == "#") {
          continue;
        } else {
          ima = "No";
        }
      } else
        continue;
    }
  }
  cout << ima << endl;
}
