#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  int a[n + 2][m + 2];
  for (int i = 0; i <= n + 1; i++) {
    for (int j = 0; j <= m + 1; i++) {
      a[i][j] = '.';
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      a[i][j] = getchar();
    }
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      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;
}
