#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e6 + 10;
char str[100][100];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) cin >> str[i][j];
  }
  bool flag = false;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      int sum = 0;
      if (str[i][j] == '#') sum++;
      if (str[i + 1][j] == '#') sum++;
      if (str[i - 1][j] == '#') sum++;
      if (str[i][j + 1] == '#') sum++;
      if (str[i][j - 1] == '#') sum++;
      if (sum == 5) flag = true;
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
