import java.util.*
import java.math.*
import java.lang.Math.*

private val readString: ()->String = {readLine()!!}
private val readInt: ()->Int = { readLine()!!.toInt() }
private val readLong: ()->Long = { readLine()!!.toLong() }
private val readListInt: ()->List<Int> = { readLine()!!.split(' ').map(String::toInt) }
private val readListLong: ()->List<Long> = { readLine()!!.split(' ').map(String::toLong) }
private val errPrintln: (String)->Unit = { msg -> System.err.println(msg) }
private val MOD = 1e9.toLong()+7


fun greedyBitFS(item: List<Pair<Int, Int>>, bonus: List<Int>, LowLimit: Int): Int {
    val N = item.size
    var res = Int.MAX_VALUE;
    for (p in 0 until (0b01 shl N)) {
        var ptn = p
        var scr = 0
        var cnt = 0
        var lv = -1
        for(i in 0 until N) {
            val vi = item[i].first
            val ci = item[i].second
            if ((ptn and 0b01) == 1) {
                scr += vi * ci + bonus[i]
                cnt += ci;
                if (scr >= LowLimit) {
                    res = min(res, cnt)
                }
            } else {
                lv = max(lv, i)
            }
            ptn = ptn shr 1
        }
        if (scr < LowLimit) {
            if (lv >= 0) {
                val v = item[lv].first
                val c = item[lv].second
                for(j in c-1 downTo  1) {
                    if (scr + v * j >= LowLimit) {
                        res = min(res, cnt + j)
                    }
                }
            }
        }
    }
    return res
}


fun main(args: Array<String>) {
    val (D,G) = readListInt()
    val item = Array<Pair<Int, Int>>(D){ Pair(0,0) }
    val C = Array<Int>(D){0}

    for(i in 0 until D) {
        val pc = readListInt()
        item[i] = Pair(100*(i+1), pc[0])
        C[i] = pc[1]
    }

    val ans = greedyBitFS(item.toList(), C.toList(), G)

    println(ans)
}
