#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> a;
  string x;
  for (int i = 0; i < h; i++) {
    cin >> x;
    a.push_back(x);
  }
  bool f[100][100] = {};
  for (int i = 0; i < h; i++)
    for (int j = 1; j < w - 1; j++) {
      if (a[i][j] == '#') {
        if (a[i][j - 1] == a[i][j + 1] && a[i][j + 1] == '.') f[i][j] = 1;
      }
    }
  for (int i = 0; i < w; i++)
    for (int j = 1; j < h - 1; j++) {
      if (a[j][i] == '#') {
        if (a[j - 1][i] == a[j + 1][i] && a[j + 1][i] == '.' && f[i][j]) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  cout << "Yes" << endl;
  return 0;
}
