#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  int res = 0;
  int fail = 0;
  string S[100000];
  cin >> H >> W;
  for (int n = 1; n <= H; n++) {
    for (int i = 1; i <= W; i++) cin >> S[n][i];
  }
  for (int n = 1; n <= H; n++) {
    for (int i = 1; i <= W; i++) {
      if (S[n][i] == '#') {
        if (S[n + 1][i] == '#' || S[n - 1][i] == '#' || S[n][i + 1] == '#' ||
            S[n][i - 1] == '#') {
          res = 1;
        } else {
          fail = 1;
          break;
        }
      }
      if (fail == 1) break;
    }
  }
  if (H == 1 && W == 1) {
    cout << "Yes" << endl;
  } else if (fail == 1) {
    cout << "No" << endl;
  } else {
    cout << "Yes" << endl;
  }
  return 0;
}
