#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h + 2][w + 2];
  for (int i = 0; i < h + 2; i++) {
    for (int j = 0; j < w + 2; j++) {
      s[i][j] = '.';
    }
  }
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; 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] == '#') {
        for (int k = -1; k <= 1; k++) {
          for (int l = -1; l <= 1; l++) {
            if (abs(k) == abs(l)) continue;
            if (s[i + k][j + l] == '#') {
              cout << "Yes" << endl;
              return 0;
            }
          }
        }
      }
    }
  }
  cout << "No" << endl;
  return 0;
}
