#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char f[W][H];
  bool flag = true;
  for (int i = 0; i < W; i++) {
    for (int j = 0; j < H; j++) cin >> f[i][j];
  }
  for (int i = 0; i < W; i++) {
    for (int j = 0; j < H; j++) {
      if (f[i][j + 1] == '#' || f[i + 1][j] == '#' || f[i][j - 1] == '#' ||
          f[i - 1][j] == '#')
        ;
      else
        flag = false;
    }
  }
  if (flag)
    cout << "Yes";
  else
    cout << "No";
}
