#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  cin >> h >> w;
  char s[h + 2][w + 2];
  for (int i = 0; i < h + 2; i++) {
    for (int j = 0; j < w + 2; j++) {
      if (i == 0 || j == 0 || i == h + 1 || j == w + 1)
        s[i][j] = '.';
      else
        cin >> s[i][j];
    }
  }
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; j++) {
      bool check = false;
      if (s[i][j] == '#') {
        if (s[i + 1][j] != '.') {
          s[i + 1][j] = '+';
          check = true;
        }
        if (s[i - 1][j] != '.') {
          s[i - 1][j] = '+';
          check = true;
        }
        if (s[i][j + 1] != '.') {
          s[i][j + 1] = '+';
          check = true;
        }
        if (s[i][j - 1] != '.') {
          s[i][j - 1] = '+';
          check = true;
        }
        if (check == false) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        cout << "Yes" << endl;
        return 0;
      }
    }
  }
}
