#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<int> dx = {1, 0, -1, 0};
vector<int> dy = {0, 1, 0, -1};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < (int)(h); i++) cin >> s.at(i);
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (s.at(i).at(j) == '#') {
        int flag = 0;
        for (int dir = 0; dir < 4; dir++) {
          int x = i + dx.at(dir), y = j + dy.at(dir);
          if (x < 0 || x >= w || y < 0 || y >= h) continue;
          if (s.at(x).at(y) == '#') flag = 1;
        }
        if (!flag) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
