#include <bits/stdc++.h>
int main() {
  int h, w;
  std::cin >> h >> w;
  std::string s[55];
  for (int i = 0; i < h; i++) std::cin >> s[i];
  int dx[4] = {0, 0, 1, -1};
  int dy[4] = {1, -1, 0, 0};
  int x, y;
  int flag = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] != '#') continue;
      for (int k = 0; k < 4; k++) {
        x = j + dx[k];
        y = i + dy[k];
        if (0 <= x && x < w && 0 <= y && y < h) {
          if (s[y][x] == '#' || s[y][x] == 'b') {
            s[y][x] = 'b';
            flag = 1;
          }
        }
      }
      if (flag) s[i][j] = 'b';
    }
  }
  bool ans = true;
  for (int i = 0; i < h; i++)
    for (int j = 0; j < w; j++)
      if (s[i][j] == '#') ans = false;
  if (ans)
    std::cout << "Yes" << std::endl;
  else
    std::cout << "No" << std::endl;
}
