#include <bits/stdc++.h>
using namespace std;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < (int)(h); i++) {
    cin >> s[i];
  }
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      bool flag = false;
      for (int k = 0; k < (int)(4); k++) {
        if (i + dy[k] >= h || i + dy[k] < 0) {
          continue;
        }
        if (j + dx[k] >= w || j + dx[k] < 0) {
          continue;
        }
        if (s[i + dy[k]][j + dx[k]] == '#') {
          flag = true;
        }
      }
      if (flag == false) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
