object Main {

  def main(args: Array[String]): Unit = {
    import scala.io.StdIn._

    val Array(h, w) = readLine().split(" ").map(_.toInt)
    val S = (0 until h).map { _ =>
      readLine().toCharArray
    }. toArray

    val iv = Array(0,0,-1,1)
    val jv = Array(1,-1,0,0)

    val res = (0 until h) forall { i =>
      (0 until w) forall { j =>
        if (S(i)(j) == '#') {
          (0 until 4) exists { v =>
            val ni = i + iv(v)
            val nj = j + jv(v)
            if (ni >= 0 && ni < h && nj >= 0 && nj < w) {
              if (S(ni)(nj) == '#') true
              else false
            } else false
          }
        } else true
      }
    }
    if (res) println("Yes")
    else println("No")
  }

}