data class PC(val p: Int, val c: Int) {
    constructor(pc: List<Int>): this(pc[0], pc[1])
}
fun main(args: Array<String>) {
    val (D, G) = listOfInt()
    val pc = Array(D) { PC(listOfInt()) }
    var ans = Int.MAX_VALUE
    var mask = 0
    for (mask in 0 until 1.shl(D)) {
        var s = 0
        var num = 0
        var rest_max = -1
        for (i in 0 until D) {
            if ((mask ushr i) and 1 != 0) {
                s += 100 * (i + 1) * pc[i].p + pc[i].c
                num += pc[i].p
            } else rest_max = i
        }
        if (s < G) {
            val s1 = 100 * (rest_max + 1)
            val need = (G - s + (s1 - 1)) / s1
            if (need >= pc[rest_max].p) continue
            num += need
        }
        ans = Math.min(ans, num)
    }
    println(ans)
}

class UnionFind(n: Int) {
    var rank: IntArray
    var par:  IntArray
    var size: IntArray
    init {
        this.rank = IntArray(n) { 0 }
        this.par  = IntArray(n) { it }
        this.size = IntArray(n) { 1 }
    }
    fun unite(x: Int, y: Int): Boolean {
        var rx = this.root(x)
        var ry = this.root(y)
        if (rx == ry) return false
        if (this.rank[rx] < this.rank[ry]) {
            val w = rx
            rx = ry
            ry = w
        } else if (this.rank[rx] == this.rank[ry]) {
            this.rank[rx] += 1
        }
        this.par[ry] = rx.toInt()
        this.size[rx] += this.size[ry]
        return true
    }
    fun find(x: Int): Int {
        if (this.par[x] == x) return x
        else {
            this.par[x] = this.find(this.par[x])
            return this.par[x]
        }
    }
    fun isSame(x: Int, y: Int): Boolean = this.root(x) == this.root(y)
    fun size(x: Int): Int = this.size[this.find(x)]
    fun root(x: Int): Int = this.find(x)
}

class Queue<T> {
    val elements = mutableListOf<T>()
    fun isEmpty() = elements.isEmpty()
    fun count() = elements.size
    fun enqueue(t: T) = elements.add(t)
    fun dequeue() = if (!isEmpty()) elements.removeAt(0) else null
    fun peek() = if (!isEmpty()) elements[0] else null
}


fun next() = readLine()!!
fun nextInt(delta: Int = 0) = Integer.parseInt(next()) + delta
fun nextLong() = next().toLong()
fun nextDouble() = next().toDouble()
fun listOfString() = next().split(" ")
fun listOfInt() = listOfString().map(String::toInt)
fun listOfLong() = listOfString().map(String::toLong)
fun listOfDouble() = listOfString().map(String::toDouble)
fun listOfInt(delta: Int = 0) = listOfString().map { Integer.parseInt(it) + delta }
fun listOfInt(vararg offset: Int) = listOfString().map { Integer.parseInt(it) }.mapIndexed { index, int -> int + offset[index % offset.size] }
fun listOfLong(delta: Long = 0L) = listOfString().map { java.lang.Long.parseLong(it) + delta }
fun listOfLong(vararg offset: Long) = listOfString().map { java.lang.Long.parseLong(it) }.mapIndexed { index, long -> long + offset[index % offset.size] }
fun listOfDouble(delta: Double = 0.0) = listOfString().map { java.lang.Double.parseDouble(it) + delta }
fun pairIntLong() = listOfLong().let { Pair(it[0].toInt(), it[1]) }
fun tripleIntIntLong() = listOfLong().let { Triple(it[0].toInt(), it[1].toInt(), it[2]) }
fun tripleIntLongLong() = listOfLong().let { Triple(it[0].toInt(), it[1], it[2]) }
fun pairIntLong(offset: Pair<Int, Long> = Pair(0, 0L)) = listOfLong().let { Pair(it[0].toInt() + offset.first, it[1] + offset.second) }
fun tripleIntIntLong(offset: Triple<Int, Int, Long> = Triple(0, 0, 0L)) = listOfLong().let { Triple(it[0].toInt() + offset.first, it[1].toInt() + offset.second, it[2] + offset.third) }
fun tripleIntLongLong(offset: Triple<Int, Long, Long> = Triple(0, 0L, 0L)) = listOfLong().let { Triple(it[0].toInt() + offset.first, it[1] + offset.second, it[2] + offset.third) }
