include <iostream>
using namespace std;

int main()
{
  int h, w;
  cin >> h >> w;
  string camp[55];
  for (int i = 0 ; i < h; i++) {
    cin >> camp[i];
  }
  
  int dh[4] = {1,  0,  -1,  0};
  int dw[4] = {0,  1,   0, -1};
  
  bool can = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      bool can2 = false;
      if (camp[i][j] == '#') {
        for (int k = 0 ; k < 4; k++) {
          int nh = i + dh[k];
          int nw = j + dw[k];
          if (nh < 0 || nh >= h) continue;
          if (nw < 0 || nw >= w) continue;
          if (camp[nh][nw] == '#') can2 = true;
        }
        if (can2 = false)
          can = false;
      }
      if (can = false)
        break;
    }
  }  
  if (can) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
