#include <bits/stdc++.h>
using namespace std;
bool check(char ary[50][50], int a, int b) {
  for (int i = 0; i < a; i++) {
    for (int j = 0; j < b; j++) {
      if (ary[i][j] == '#') {
        if (ary[i - 1][j] != '#' && ary[i + 1][j] != '#' &&
            ary[i][j - 1] != '#' && ary[i][j + 1] != '#') {
          return false;
        }
      }
    }
  }
  return true;
}
int main() {
  char ary[50][50] = {'-'};
  int a, b;
  memset(ary, 0, 50 * 50);
  cin >> a >> b;
  for (int i = 0; i < a; i++) {
    cin >> ary[i + 1] + 1;
  }
  bool yes = check(ary, a, b);
  if (yes) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
