#include <bits/stdc++.h>
int main() {
  int h, w;
  std::cin >> h >> w;
  char grid[h][w];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      std::cin >> grid[i][j];
    }
  }
  int flg = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (grid[i][j] == '#') {
        if (i - 1 >= 0) {
          if (grid[i - 1][j] == '#') break;
        }
        if (h > i + 1) {
          if (grid[i + 1][j] == '#') break;
        }
        if (j - 1 >= 0) {
          if (grid[i][j - 1] == '#') break;
        }
        if (w > j + 1) {
          if (grid[i][j + 1] == '#') break;
        }
        flg++;
      }
    }
  }
  if (flg == 0) {
    std::cout << "Yes" << std::endl;
  } else {
    std::cout << "No" << std::endl;
  }
  return 0;
}
