#include <bits/stdc++.h>
using namespace std;
static const int MAX = 50;
int main() {
  int h, w;
  string grid[MAX + 1];
  cin >> h >> w;
  for (int i = 0; i < h; ++i) {
    cin >> grid[i];
  }
  const int dx[4] = {0, 1, -1, 0};
  const int dy[4] = {-1, 0, 0, 1};
  bool canDraw = true;
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (grid[i][j] != '#') continue;
      bool can = false;
      for (int k = 0; k < 4; ++k) {
        int ni = i + dy[k];
        int nj = j + dx[k];
        if (ni < 0 or h <= ni) continue;
        if (nj < 0 or w <= nj) continue;
        if (grid[ni][nj] == '#') {
          can = true;
          break;
        }
      }
      if (!can) {
        canDraw = false;
        break;
      }
    }
  }
  if (canDraw)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
