#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const int INF = 1e9;
const long long MOD = 1000000007;
using Graph = vector<vector<int>>;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int h, w;
  cin >> h >> w;
  vector<vector<char>> s(h, vector<char>(w));
  for (int i = 0; i < (h); i++) {
    for (int j = 0; j < (w); j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 1; i < h - 1; ++i) {
    for (int j = 1; j < w - 1; ++j) {
      if (s[i][j] == '#' && (s[i - 1][j] == '#' || s[i][j - 1] == '#' ||
                             s[i][j + 1] == '#' || s[i + 1][j] == '#')) {
        cout << "Yes"
             << "\n";
        ;
        return 0;
      }
    }
  }
  cout << "No"
       << "\n";
  ;
}
