#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const string YES = "Yes";
const string NO = "No";
void solve(long long H, long long W, std::vector<std::string> s) {
  vector<pair<ll, ll>> dir{pair<ll, ll>(-1, 0), pair<ll, ll>(1, 0),
                           pair<ll, ll>(0, -1), pair<ll, ll>(0, 1)};
  for (long long i = 0; i < H; i++) {
    for (long long j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        bool ok = false;
        for (long long k = 0; k < 4; k++) {
          ll tmpi = i + dir[k].first;
          ll tmpj = j + dir[k].second;
          if (!(tmpi < 0 || tmpi > H - 1 || tmpj < 0 || tmpj > W - 1)) {
            if (s[tmpi][tmpj] == '#') {
              ok = true;
            }
          }
        }
        if (!ok) {
          cout << "No" << endl;
          return;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return;
}
int main() {
  long long H;
  scanf("%lld", &H);
  long long W;
  scanf("%lld", &W);
  std::vector<std::string> s(W);
  for (int i = 0; i < W; i++) {
    std::cin >> s[i];
  }
  solve(H, W, std::move(s));
  return 0;
}
