#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, ans = 0, abc = 0;
  char s[50][50];
  cin >> a >> b;
  for (int i = 0; i < (a); i++) {
    for (int j = 0; j < (b); j++) {
      cin >> s[i][j];
      if (s[i][j] == '#') abc++;
    }
  }
  for (int i = 0; i < (a); i++) {
    for (int j = 0; j < (b); j++) {
      if (s[i][j] == '#') {
        if (s[i + 1][j] == '#' || s[i - 1][j] == '#' || s[i][j + 1] == '#' ||
            s[i][j] == '#')
          ans++;
      }
    }
  }
  if (abc == ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
