#include <bits/stdc++.h>
using namespace std;
long long gcm(long long a, long long b);
int main() {
  vector<int> dx = {0, -1, 1, 0};
  vector<int> dy = {-1, 0, 0, 1};
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < h; i++) cin >> s[i];
  bool ans = true;
  bool sharp = false;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        sharp = true;
        bool ok = false;
        for (int t = 0; t < 4; t++) {
          int x = i + dx[t];
          int y = j + dy[t];
          if (0 <= x && x < h && 0 <= y && y < w) {
            if (s[x][y] == '#') {
              ok = true;
            }
          }
        }
        if (!(ok)) {
          ans = false;
          break;
        }
      }
    }
    if (!(ans)) break;
  }
  if (ans && sharp)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
