#include <bits/stdc++.h>
int MOD = 1000000000 + 7;
int INF = 1e6;
using namespace std;
string alphabet("abcdefghijklmnopqrstuvwxyz");
int main() {
  int a[50][50] = {};
  int h, w;
  cin >> h >> w;
  for (int i = (1); i <= (w); ++i) {
    for (int j = (1); j <= (h); ++j) {
      char c;
      cin >> c;
      if (c == '#') a[j][i] = 1;
    }
  }
  for (int i = (1); i <= (w); ++i) {
    for (int j = (1); j <= (h); ++j) {
      if (!(a[j + 1][i] || a[j - 1][i] || a[j][i + 1] || a[j][i - 1])) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
}
