#include <bits/stdc++.h>
using namespace std;
const int N = 1000000;
const long long mod = 1000000007;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(w + 1);
  for (long long int i = 1; i < w + 1; i++) cin >> s[i];
  char a[h + 10][w + 10];
  for (long long int i = 1; i < h + 1; i++) {
    for (long long int j = 1; j < w + 1; j++) {
      a[i][j] = s[i][j];
    }
  }
  bool flag = true;
  for (long long int i = 1; i < h + 1; i++) {
    for (long long int j = 1; j < w + 1; j++) {
      if (a[i][j] == '#') {
        int count = 0;
        if (a[i + 1][j] == '#') count++;
        if (a[i - 1][j] == '#') count++;
        if (a[i][j + 1] == '#') count++;
        if (a[i][j - 1] == '#') count++;
        if (count == 0) {
          flag = false;
          break;
        }
      }
    }
  }
  if (flag)
    std::cout << "Yes" << std::endl;
  else
    std::cout << "No" << std::endl;
}
