#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
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[i];
  }
  bool J = 1;
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      bool l = 0;
      for (int k = 0; k < (int)(4); k++) {
        if (i + dx[k] >= h || j + dy[k] >= w || i + dx[k] < 0 || j + dy[k] < 0)
          continue;
        if (s[i + dx[k]][j + dy[k]] == '#') l = 1;
      }
      if (!l) J = 0;
    }
  }
  if (J)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
