object Main extends App {
	val Array(d, g) = scala.io.StdIn.readLine.split(" ").map(_.toInt)
	val p = new Array[Int](d)
	val c = new Array[Int](d)

	for(i<-0 until d){
		val Array(tp1, tp2) = scala.io.StdIn.readLine.split(" ").map(_.toInt)
		p(i) = tp1
		c(i) = tp2 + (i+1)* 100 * tp1
	}

	var ans = 1e9.toInt

	for(i <- 0 to ((0x1 << d) - 1)){
		var tp   = 0
		var cn 	 = 0
		var rest = -1

		for(j<-0 until d){
			if(((i >> j) & 0x1) == 0x1){
				tp += c(j)
				cn += p(j)
			}else{
				rest = j
			}
		}

		if(tp < g && rest != -1){
			val s1 = 100 * (rest + 1)
			val need = (g - tp)/s1
			if(need < p(rest)){
				cn += need.toInt
				ans = math.min(ans, cn)
			}
		}

		if(tp >= g){
			ans = math.min(ans, cn)
		}
	}

	println(ans)
}