#include <bits/stdc++.h>
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  int vx[4] = {1, 0, -1, 0};
  int vy[4] = {0, 1, 0, -1};
  for (int i = 0; i < h; i++) {
    bool can_paint = false;
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int nextx = i + vx[k], nexty = j + vy[k];
          if (nextx >= 0 && nextx < w && nexty >= 0 && nexty < h &&
              s[nexty][nextx] == '#') {
            can_paint = true;
            break;
          }
        }
      }
    }
    if (can_paint == false) {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
}
