#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
long long dx[] = {1, 0, -1, 0};
long long dy[] = {0, 1, 0, -1};
constexpr ll mod = 1e9 + 7;
constexpr ll inf = INT32_MAX / 2;
constexpr ll INF = LLONG_MAX / 2;
constexpr long double eps = DBL_EPSILON;
constexpr long double pi = 3.141592653589793238462643383279;
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
ll fact(long long i) {
  if (i == 0) return 1;
  return (fact(i - 1)) * i % mod;
}
ll gcd(ll a, ll b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
long long keta(ll n) {
  if (n == 0) return 1;
  long long count = 0;
  while (n != 0) {
    n /= 10;
    count++;
  }
  return count;
}
ll ketasum(ll n) {
  ll sum = 0;
  while (n != 0) {
    sum += n % 10;
    n /= 10;
  }
  return sum;
}
signed main() {
  long long h, w;
  cin >> h >> w;
  vector<vector<bool>> bo(h, vector<bool>(w));
  vector<P> v;
  for (long long i = 0; i < (long long)(h); i++) {
    for (long long j = 0; j < (long long)(w); j++) {
      char c;
      cin >> c;
      if (c == '#') {
        bo[i][j] = true;
        v.push_back({i, j});
      } else
        bo[i][j] = false;
    }
  }
  bool ok = true;
  for (long long i = 0; i < (long long)(v.size()); i++) {
    for (long long i = 0; i < (long long)(4); i++) {
      long long x = v[i].first + dx[i], y = v[i].second + dy[i];
      if (x < 0 || x >= h || y < 0 || y >= w) continue;
      if (bo[x][y]) break;
      if (i == 3) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
