#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w, i, j, flag = 1;
  cin >> h >> w;
  char s[h][w];
  for (i = 0; i < h; i++)
    for (j = 0; j < w; j++) cin >> s[i][j];
  for (i = 0; i < h; i++) {
    for (j = 0; j < h; j++) {
      if (s[i][j] == '#') {
        if (s[i + 1][j] != '#' && s[i][j + 1] != '#' && s[i][j - 1] != '#' &&
            s[i - 1][j] != '#')
          flag = 0;
        break;
      }
    }
  }
  if (flag == 0)
    cout << "NO";
  else
    cout << "YES";
  return 0;
}
