import java.util.Scanner


object Main {
  def main(args: Array[String]): Unit = {
    val sc = new Scanner(System.in)
    val h, w = sc.nextInt()
    
    val map = Array.ofDim[Char](h, w)
    
    for (i <- map.indices) {
      val a = sc.next().toCharArray
      map(i) = a
    }
    
    var ans = "Yes"
    
    for (i <- 0 until h) {
      for (j <- 0 until w) {
        if (map(i)(j) == '#') {
          val arr = Array((i + 1, j), (i, j + 1), (i - 1, j), (i, j - 1)).filter(a => 0 <= a._1 && a._1 < h && 0 <= a._2 && a._2 < w)
          val m = arr.map(a => map(a._1)(a._2))
          if (!m.contains('#')) {
            ans = "No"
          }
        }
      }
    }
    
    println(ans)
  }
  
  def printArray[T](arr: Array[T]): Unit = {
    for (i <- arr.indices) {
      print(s"${arr(i)} ")
    }
    println()
  }
}
