#include <bits/stdc++.h>
using namespace std;
int n, m, f = 0;
char s[51][51];
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) cin >> s[i][j];
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if ((s[i][j] == '#') && (s[i - 1][j] == '#' && s[i + 1][j] == '#' &&
                               s[i][j - 1] == '#' && s[i][j + 1] == '#'))
        f++;
    }
  }
  if (f == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
