#include <bits/stdc++.h>
using namespace std;
int main() {
  const int dx[] = {1, -1, 0, 0};
  const int dy[] = {0, 0, 1, -1};
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  for (int i = 0; i < (int)s.size(); i++) cin >> s[i];
  bool IsOk = true;
  for (int i = 0; i < (H); i++)
    for (int j = 0; j < (W); j++) {
      if (s[i][j] == '#') {
        bool IsNextOk = false;
        for (int k = 0; k < (4); k++) {
          int y = i + dy[k];
          int x = j + dx[k];
          if (x >= 0 && x < H && y >= 0 && y < W) {
            if (s[y][x] == '#') IsNextOk = true;
          }
        }
        if (!IsNextOk) IsOk = false;
      }
    }
  if (IsOk)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
