#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string buff;
  char s[60][60] = {' '};
  for (int i = 0; i < H; i++) {
    cin >> buff;
    for (int j = 0; j < W; j++) {
      s[i + 1][j + 1] = buff.at(j);
    }
  }
  const char brack = '#';
  string result = "";
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (s[i][j] == brack) {
        result = "No";
        if (s[i - 1][j] == brack) result = "Yes";
        if (s[i + 1][j] == brack) result = "Yes";
        if (s[i][j - 1] == brack) result = "Yes";
        if (s[i][j + 1] == brack) result = "Yes";
        if (result == "No") break;
      }
    }
    if (result == "No") break;
  }
  if (result == "") result = "No";
  cout << result << endl;
  return 0;
}
