#include <bits/stdc++.h>
using namespace std;
template <class A>
void pr(A a) {
  cout << a;
  cout << '\n';
}
template <class A, class B>
void pr(A a, B b) {
  cout << a << ' ';
  pr(b);
}
template <class A, class B, class C>
void pr(A a, B b, C c) {
  cout << a << ' ';
  pr(b, c);
}
template <class A, class B, class C, class D>
void pr(A a, B b, C c, D d) {
  cout << a << ' ';
  pr(b, c, d);
}
template <class A>
void PR(A a, long long n) {
  for (long long i = (long long)(0); i < (long long)(n); i++) {
    if (i) cout << ' ';
    cout << a[i];
  }
  cout << '\n';
}
long long check(long long n, long long m, long long x, long long y) {
  return x >= 0 && x < n && y >= 0 && y < m;
}
const long long MAX = 1e9 + 7, MAXL = 1LL << 61, dx[4] = {-1, 0, 1, 0},
                dy[4] = {0, 1, 0, -1};
void Main() {
  long long n, m;
  cin >> n >> m;
  string s[n];
  for (long long i = (long long)(0); i < (long long)(n); i++) cin >> s[i];
  for (long long i = (long long)(0); i < (long long)(n); i++) {
    for (long long j = (long long)(0); j < (long long)(m); j++) {
      if (s[i][j] != '#') continue;
      int c = 0;
      for (long long k = (long long)(0); k < (long long)(4); k++) {
        int x = i + dx[k], y = j + dy[k];
        if (check(n, m, x, y) && s[i][j] == '#') c++;
      }
      if (!c) {
        pr("No");
        return;
      }
    }
  }
  pr("Yes");
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  Main();
  return 0;
}
