#include <bits/stdc++.h>
int main() {
  int h, w;
  std::cin >> h >> w;
  std::vector<std::string> s(h);
  for (int i = 0; i < h; i++) {
    std::cin >> s[i];
  }
  std::vector<int> dx = {-1, 0, 0, 1};
  std::vector<int> dy = {0, -1, 1, 0};
  std::string ans = "Yes";
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      int cnt = 0;
      if (s[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int ni = i + dx[k];
          int nj = j + dy[k];
          if (0 <= ni && ni < w && 0 <= nj && nj < h && s[ni][nj] == '.') {
            ++cnt;
          }
        }
      }
      if ((i == 0 || i == h - 1) && (j == 0 || j == w - 1)) {
        if (cnt == 2) {
          ans = "No";
          break;
        }
      } else if (cnt == 4) {
        ans = "No";
        break;
      }
    }
  }
  std::cout << ans << std::endl;
  return 0;
}
