#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<int>> s(h + 2, vector<int>(w + 2, '.'));
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i + 1][j + 1];
    }
  }
  int mvx[4] = {0, 1, 0, -1};
  int mvy[4] = {1, 0, -1, 0};
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i + 1][j + 1] == '#') {
        bool flag = false;
        for (int nx = 0; nx < 4; nx++) {
          if (s[i + 1 + mvx[nx]][j + 1 + mvy[j]] == '#') {
            flag = true;
          }
        }
        if (!flag) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
}
