#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  char s[51][51];
  string result;
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] == '#' || s[i + 1][j] == '#' || s[i][j - 1] == '#' ||
            s[i][j + 1] == '#') {
          result = "Yes";
        } else {
          result = "No";
        }
      }
    }
  }
  cout << result << endl;
}
