#include <bits/stdc++.h>
using namespace std;
vector<int> arr;
stack<int> st;
queue<int> qu;
queue<pair<int, int> > qu2;
priority_queue<int> pq;
static const int NIL = -1;
static const int INF = 1000000007;
double dot_product(complex<double> a, complex<double> b) {
  return (conj(a) * b).real();
}
double cross_product(complex<double> a, complex<double> b) {
  return (conj(a) * b).imag();
}
complex<double> projection(complex<double> p, complex<double> b) {
  return b * dot_product(p, b) / norm(b);
}
int s[52][52];
int main() {
  int h, w;
  cin >> h >> w;
  int s[h][w];
  for (int i = 1; i <= (int)(h); i++) {
    for (int j = 1; j <= (int)(w); j++) {
      char d;
      cin >> d;
      if (d == '#') {
        s[i][j] = 1;
      } else {
        s[i][j] = 0;
      }
    }
  }
  for (int i = 1; i <= (int)(h); i++) {
    for (int j = 1; j <= (int)(w); j++) {
      if (s[i][j] == 1) {
        if (s[i][j - 1] == 1 || s[i][j + 1] == 1 || s[i - 1][j] == 1 ||
            s[i + 1][j] == 1) {
          continue;
        } else {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
