#include <bits/stdc++.h>
int main() {
  int h, w;
  std::cin >> h >> w;
  std::string str[h];
  for (int i = 0; (i < h); ++i) {
    std::cin >> str[i];
  }
  const int di[4] = {-1, 1, 0, 0};
  const int dj[4] = {0, 0, -1, 1};
  for (int i = 0; (i < h); ++i) {
    for (int j = 0; (j < w); ++j) {
      if (str[i][j] == '.') continue;
      int num = 0;
      for (int k = 0; (k < 4); ++k) {
        int ii = i + di[k];
        if ((ii < 0) || (ii >= h)) continue;
        int jj = j + dj[k];
        if ((jj < 0) || (jj >= h)) continue;
        if (str[ii][jj] == '#') ++num;
      }
      if (num == 0) {
        std::cout << "No" << std::endl;
        return 0;
      }
    }
  }
  std::cout << "Yes" << std::endl;
  return 0;
}
