#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char ch[h + 1][w + 1];
  for (int y = 0; y <= h; y++) {
    for (int x = 0; x <= w; x++) {
      cin >> ch[y][x];
    }
  }
  for (int y = 1; y < h; y++) {
    for (int x = 1; x < w; x++) {
      if (ch[y][x] == '.') continue;
      if (ch[y - 1][x] == '#' || ch[y + 1][x] == '#' || ch[y][x - 1] == '#' ||
          ch[y][x + 1] == '#') {
        cout << "Yes" << endl;
        return 0;
      }
    }
  }
  cout << "No" << endl;
}
