import scala.io.StdIn

object Main extends App {
  val Array(h, w) = StdIn.readLine().split(' ').map(_.toInt)
  val matrix = Array.fill[String](h + 2, w + 2)("")

  (1 to h).foreach { i =>
    matrix(i) = (" " + StdIn.readLine() + " ").split("")
  }

  def judge(i: Int, j: Int): Boolean = {
    (matrix(i)(j) == "#" && matrix(i + 1)(j) == "#") ||
      (matrix(i)(j) == "#" && matrix(i)(j + 1) == "#") ||
      (matrix(i)(j) == "#" && matrix(i - 1)(j) == "#") ||
      (matrix(i)(j) == "#" && matrix(i)(j - 1) == "#")
  }

  var good = true
  var ti = 1
  while (good && ti <= h) {
    var tj = 1
    while (good && tj <= w) {
      good = judge(ti, tj)
      tj += 1
    }
    ti += 1
  }

  println(if (good) "Yes" else "No")
  
}