#include <bits/stdc++.h>
using namespace std;
int main() {
  char a[55][55];
  int b[55][55] = {0};
  int h, w;
  cin >> h >> w;
  int y = 0;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> a[i][j];
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; i < w; j++) {
      if (a[i][j] == '#') {
        if ((i - 1) >= 0 && i + 1 < h) {
          if (a[i - 1][j] == '#' || a[i + 1][j] == '#') {
            y = 2;
            continue;
          }
        } else if (j - 1 >= 0 && j + 1 < w) {
          if (a[i][j - 1] == '#' || a[i][j + 1] == '#') {
            y = 1;
            continue;
          }
        }
        break;
      }
    }
    if (y == 0) break;
  }
  if (y == 0)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
