#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string x;
  int *s;
  cin >> h >> w;
  s = new int[h * (w + 1)]();
  for (int i = 0; i < w; i++) {
    cin >> x;
    for (int j = 0; j < h; j++) {
      if (x[j] == '#') s[j + w * i] = 1;
    }
  }
  for (int i = 0; i < h * w; i++) {
    if (s[i] == 1) {
      if (s[i + w] == 0) {
        if ((i + 1) % w) {
          if (s[i + 1] == 0) {
            cout << "No\n";
            return 0;
          } else
            s[i + 1]++;
        } else {
          cout << "No\n";
          return 0;
        }
      } else
        s[i + w]++;
    } else if (s[i] != 0 && s[i] != 1) {
      if (s[i + 1] != 0)
        if ((i + 1) % w) s[i + 1]++;
      if (s[i + w] != 0) s[i + w]++;
    }
  }
  cout << "Yes\n";
}
