#include <bits/stdc++.h>
using namespace std;
const int INF = 1001001001;
const long long LINF = 1e18;
const long long mod = 1e9 + 7;
template <typename T>
T gcd(T a, T b) {
  if (a < b) gcd(b, a);
  T r;
  while ((r = a % b)) {
    a = b;
    b = r;
  }
  return b;
}
char c[55][55];
long long H, W;
int main() {
  cin >> H >> W;
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      cin >> c[i][j];
    }
  }
  long long count = 0;
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (c[i][j] == '#' && (c[i - 1][j] != '#' || c[i + 1][j] != '#' ||
                             c[i][j - 1] != '#' || c[i][j + 1] != '#')) {
        count++;
      }
    }
  }
  cout << (count == 0 ? "Yes" : "No") << endl;
  return 0;
}
