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