#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using VI = vector<int>;
using VVI = vector<vector<int>>;
using P = pair<int, int>;
int v[4] = {1, 0, -1, 0};
int u[4] = {0, 1, 0, -1};
int main() {
  int h, w;
  cin >> h >> w;
  string s[h];
  for (int i = 0; i < (int)(h); i++) cin >> s[i];
  bool ans = true;
  for (int i = 0; i < (int)(h); i++)
    for (int j = 0; j < (int)(w); j++) {
      if (s[i][j] == '#') {
        bool flag = false;
        for (int k = 0; k < (int)(4); k++) {
          int ik = i + v[k];
          int jk = j + u[k];
          if (0 <= ik && ik < h && 0 <= jk && jk < w) {
            if (s[ik][jk] == '#') flag = true;
          }
        }
        ans = flag;
      }
    }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
