#include <bits/stdc++.h>
using namespace std;
using Int = long long;
signed main() {
  Int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (Int i = 0; i < h; i++) cin >> s[i];
  vector<string> t(h, string(w, '.'));
  for (Int i = 0; i < h; i++) {
    for (Int j = 0; j < w; j++) {
      if (s[i][j] != '#') continue;
      if (j + 1 < w && s[i][j + 1] == '#') {
        t[i][j] = '#';
        t[i][j + 1] = '#';
      }
      if (i + 1 < w && s[i + 1][j] == '#') {
        t[i][j] = '#';
        t[i + 1][j] = '#';
      }
    }
  }
  cout << (s == t ? "Yes" : "No") << endl;
  return 0;
}
