#include <bits/stdc++.h>
using namespace std;
const long long INF = 1LL << 60;
int main() {
  int h, w;
  cin >> h >> w;
  char A[h][w];
  bool can = true;
  for (int i = 1; i <= (int)(h); i++) {
    for (int j = 1; j <= (int)(w); j++) {
      cin >> A[i][j];
    }
  }
  for (int i = 1; i <= (int)(h); i++) {
    for (int j = 1; j <= (int)(w); j++) {
      if (A[i][j] == '#' && A[i - 1][j] != '#' && A[i + 1][j] != '#' &&
          A[i][j - 1] != '#' && A[i][j + 1] != '#') {
        can = false;
      }
    }
  }
  if (can)
    cout << "Yes" << endl;
  else {
    cout << "No" << endl;
  }
}
