import scala.io.StdIn._
object Main extends App {
  val Array(h, w) = readLine.split(" ").map(_.toInt)
  val array = Array.fill(h + 2, w + 2)('.')
  (1 to h).foreach { i =>
    val s = readLine
    (1 to w).foreach { j =>
      array(i)(j) = s(j - 1)
    }
  }
  var res = false
  for (i <- 1 to h) {
    val target = array(i)
    for (j <- 1 to w) {
      if (target(j) == '#') {
        if (array(i - 1)(j) == '.' &&
            array(i + 1)(j) == '.' &&
            array(i)(j - 1) == '.' &&
            array(i)(j + 1) == '.') {
          res = true
        }
      }
    }
  }
  println(if(res) "No" else "Yes")
}
