#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  int a[h + 5][w + 5];
  for (int i = 0; i <= h + 1; ++i) {
    for (int j = 0; j <= w + 1; ++j) {
      a[i][j] = '.';
    }
  }
  for (int i = 1; i <= h; ++i) {
    for (int j = 1; j <= w; ++j) {
      cin >> a[i][j];
    }
  }
  for (int i = 1; i <= h; ++i) {
    for (int j = 1; i <= w; ++i) {
      if (a[i][j] == '#' && (a[i + 1][j] != '#' && a[i - 1][j] != '#' &&
                             a[i][j + 1] != '#' && a[i][j - 1] != '#')) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
