#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool amax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool amin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
int GCD(int a, int b) { return b ? GCD(b, a % b) : a; }
long long GCD(long long a, long long b) { return b ? GCD(b, a % b) : a; }
int LCM(int a, int b) { return a * b / GCD(a, b); }
long long LCM(long long a, long long b) { return a * b / GCD(a, b); }
struct aaa {
  aaa() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  };
} aaaaaaa;
const int INF = 1001001001;
const long long LINF = 1001001001001001001ll;
const int MOD = 1e9 + 7;
const double EPS = 1e-9;
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
signed main() {
  int h, w;
  cin >> h >> w;
  vector<string> c(h + 1);
  int cnt{};
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) cin >> c[i][j];
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (c[i][j] == '#' && c[i][j - 1] != '#' && c[i - 1][j] != '#' &&
          c[i][j + 1] != '#' && c[i + 1][j] != '#')
        cnt++;
    }
  }
  if (cnt == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
