#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
long long gcd(long long x, long long y) { return y ? gcd(y, x % y) : x; }
long long factorial(long long n) {
  long long answer = 1;
  while (n > 1) {
    answer *= n;
    answer %= mod;
    n--;
  }
  return answer;
}
long long combination(long long n, long long r) {
  return factorial(n) / (factorial(r) * factorial(n - r));
}
long long permutation(long long n, long long r) {
  return factorial(n) / factorial(n - r);
}
template <typename T>
void remove(std::vector<T>& vector, unsigned int index) {
  vector.erase(vector.begin() + index);
}
map<long long, long long> prime_factor(long long n) {
  map<long long, long long> ret;
  for (long long i = 2; i * i <= n; i++) {
    while (n % i == 0) {
      ret[i]++;
      n /= i;
    }
  }
  if (n != 1) ret[n] = 1;
  return ret;
}
vector<long long> divisor(long long n) {
  vector<long long> ret;
  for (long long i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i * i != n) ret.push_back(n / i);
    }
  }
  sort(begin(ret), end(ret));
  return (ret);
}
bool compare_by_b(pair<long long, long long> a, pair<long long, long long> b) {
  if (a.second != b.second) {
    return a.second < b.second;
  } else {
    return a.first < b.first;
  }
}
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  for (int i = 0; i < (w); i++) {
    for (int j = 0; j < (h); j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < (w); i++) {
    for (int j = 0; j < (h); j++) {
      if (s[i][j] == '#') {
        if (s[i - 1][j] != '#' && s[i][j + 1] != '#' && s[i + 1][j] != '#' &&
            s[i][j - 1] != '#') {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
