#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[100][100];
  int z = 0;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (s[i][j] == '#' && s[i][j + 1] != '#' && s[i][j - 1] != '#' &&
          s[i + 1][j] != '#' && s[i + 1][j] != '#')
        z++;
    }
  }
  if (z == 0)
    cout << "Yes\n";
  else
    cout << "No\n";
}
