import scala.io.{StdIn => in}

object Main extends App {
  val Array(n, h) = in.readLine.split(" ").map(_.toInt)
  val k = Iterator.continually(in.readLine)
    .take(n)
    .map(_.split(" ").map(_.toInt))
    .toArray
    .transpose
  
  val ans = {
    val a = k(0).max
    val b = k(1).filter(_ > a).sorted(Ordering[Int].reverse)

    def rec(hp:Int, cnt:Int):(Int,Int) = {
      if(hp <= 0 || cnt >= b.size) (hp,cnt)
      else rec(hp-b(cnt),cnt+1)
    }

    val (hp,cnt) = rec(h,0)
    if(hp <= 0) cnt else cnt + (hp + (a-1)) / a
  }

  println(ans)
}