#include <bits/stdc++.h>
using namespace std;
int dy[] = {0, 0, 1, -1, 0};
int dx[] = {1, -1, 0, 0, 0};
int main(int argc, char const *argv[]) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int h, w, cnt = 0;
  cin >> h >> w;
  char s[50][50];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; j++) {
      if (s[i][j] == '#' && s[i][j - 1] != '#' && s[i - 1][j] != '#' &&
          s[i][j + 1] != '#' && s[i + 1][j] != '#')
        cnt++;
    }
  }
  if (cnt == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
