#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  ;
  char s[51][51];
  for (int i = 0; i < w; i++) {
    for (int j = 0; j < h; j++) {
      cin >> s[i][j];
    }
  }
  int c = 1;
  for (int i = 0; i < w; i++) {
    for (int j = 0; j < h; j++) {
      if (s[i][j] == '.' && s[i - 1][j] == '#' && s[i + 1][j] == '#' &&
          s[i][j - 1] == '#' && s[i][j + 1] == '#')
        c *= 0;
    }
  }
  if (c == 0) {
    cout << "No" << endl;
  } else {
    cout << "Yes" << endl;
  }
  return 0;
}
