import scala.math.ceil

object Main {
  def main(args:Array[String]) = {
    val sc = new java.util.Scanner(System.in)
    val d, g = sc.nextInt
    val table : List[List[Int]] = List.fill(d, 2)(sc.nextInt)

    val is = 0 until d

    var n = 0
    var gLeft = g
    var psLeft= is.map(table(_)(0))
    val cs = is.map(table(_)(1))
    while(gLeft > 0) {
      val isSufficient = is.filter(i => gLeft.toFloat / 100 / (i + 1) <= psLeft(i))
      if(isSufficient.nonEmpty) {
        n = n + ceil(gLeft.toFloat / 100 / (isSufficient.max + 1)).toInt
        gLeft = 0
      } else {
        val iMax = is.maxBy(i =>
          ((i + 1) * 100 * psLeft(i) + cs(i)).toFloat / psLeft(i)
        )
        n = n + psLeft(iMax)
        gLeft = gLeft - (iMax + 1) * psLeft(iMax) * 100 + cs(iMax)
        psLeft = psLeft.updated(iMax, 0)
      }
    }
    println(n)
  }
}