#include <bits/stdc++.h>
using ll = long long;
using namespace std;
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
const ll INF = 1LL << 60;
ll h, w;
vector<vector<char>> s(100, vector<char>(100));
int main() {
  cin >> h >> w;
  for (int i = (1); i < (h + 1); i++)
    for (int j = (1); j < (w + 1); j++) cin >> s[i][j];
  bool flag = false;
  for (int i = (1); i < (h + 1); i++) {
    for (int j = (1); j < (w + 1); j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] == '#')
          flag = true;
        else if (s[i + 1][j] == '#')
          flag = true;
        else if (s[i][j - 1] == '#')
          flag = true;
        else if (s[i][j + 1] == '#')
          flag = true;
      }
    }
  }
  if (flag)
    cout << "Yes"
         << "\n";
  else
    cout << "No"
         << "\n";
  return 0;
}
