#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
template <class T>
using V = vector<T>;
const ll inf = (1e18);
const ll mod = 1000000007;
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll c, ll d) { return c / gcd(c, d) * d; }
struct __INIT {
  __INIT() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
  }
} __init;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
V<int> dx = {1, 0, -1, 0}, dy = {0, -1, 0, 1};
int main() {
  int h, w;
  cin >> h >> w;
  V<V<bool>> a(h, V<bool>(w, true));
  V<string> s(h);
  for (int i = 0; i < h; i++) cin >> s[i];
  P t = P(-1, -1);
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        t.first = i;
        t.second = j;
      }
    }
    if (t.first != -1) break;
  }
  if (t.first == -1) {
    cout << "Yes" << endl;
    return 0;
  }
  queue<P> q;
  a[t.first][t.second] = false;
  q.push(t);
  bool ok = true;
  while (!q.empty()) {
    P now = q.front();
    q.pop();
    int cnt = 0;
    for (int i = 0; i < 4; i++) {
      int nx = now.first + dx[i], ny = now.second + dy[i];
      if (nx < 0 || nx >= h || ny < 0 || ny >= w) {
        continue;
      }
      if (s[nx][ny] != '#') continue;
      cnt++;
      if (!a[nx][ny]) continue;
      a[nx][ny] = false;
      q.push(P(nx, ny));
    }
    if (cnt == 0) ok = false;
  }
  if (!ok)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
}
