#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w, f = 1;
  char a[50][50];
  cin >> h >> w;
  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; j < w; j++) {
      if (a[i][j + 1] == '#' || a[i][j - 1] == '#' || a[i + 1][j] == '#' ||
          a[i - 1][j] == '#') {
        f = 0;
      } else {
        f = 1;
        break;
      }
    }
  }
  if (f == 0) {
    cout << "Yes\n";
  } else {
    cout << "No\n";
  }
}
