#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, n = 0, m = 0, f = 0;
  cin >> n >> m;
  if ((n >= 1 && n <= 50) && (m >= 1 && m <= 50)) {
    char s[n][m];
    for (i = 0; i < n; i++) {
      for (j = 0; j < m; j++) {
        cin >> s[i][j];
      }
    }
    for (i = 0; i < n; i++) {
      for (j = 0; j < m; j++) {
        if ((s[i][j] == '#') && (s[i - 1][j] == '#' && s[i + 1][j] == '#' &&
                                 s[i][j - 1] == '#' && s[i][j + 1] == '#')) {
          f = 1;
          break;
        }
      }
    }
    if (f == 1) {
      cout << "Yes" << endl;
    }
    if (f == 0) {
      cout << "No" << endl;
    }
  }
  return 0;
}
