#include <bits/stdc++.h>
char field[52][52] = {};
int main(void) {
  int h, w;
  std::cin >> h >> w;
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) std::cin >> field[i][j];
  const int dir[5] = {0, -1, 0, 1, 0};
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      bool f = false;
      for (int k = 0; k < 4; k++)
        if (field[i][j] == '#' && field[i + dir[k]][j + dir[k + 1]] == '#') {
          f = true;
        }
      if (!f) {
        std::cout << "No" << std::endl;
        return 0;
      }
    }
  std::cout << "Yes" << std::endl;
  return 0;
}
