#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);
  for (long long int i = 0; i < w; i++) cin >> s[i];
  char a[h][w];
  for (long long int i = 0; i < h; i++) {
    for (long long int j = 0; j < w; j++) {
      a[i][j] = s[i][j];
    }
  }
  bool flag = true;
  for (long long int i = 0; i < h; i++) {
    for (long long int j = 0; j < w; j++) {
      if (a[i][j] == '#') {
        int count = 0;
        if (i < h - 1) {
          if (a[i + 1][j] == '#') count++;
        }
        if (i > 0) {
          if (a[i - 1][j] == '#') count++;
        }
        if (j < w - 1) {
          if (a[i][j + 1] == '#') count++;
        }
        if (j > 0) {
          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;
}
