import java.lang.Math.min

fun main(args: Array<String>) {
    val (d, g) = readIntList()
    val p = List(d) { readIntList() }

    var ans = Int.MAX_VALUE
    for (mask in 0 until (1 shl d)) {
        var s = 0
        var num = 0
        var restMax = -1
        for (i in 0 until d) {
            if ((mask shr i) and 1 == 1) {
                s += 100 * (i + 1) * p[i][0] + p[i][1]
                num += p[i][0]
            } else {
                restMax = i
            }
        }
        if (s < g) {
            var s1 = 100 * (restMax + 1)
            var need = (g - s + s1 - 1) / s1
            if (need >= p[restMax][0]) continue
            num += need
        }
        ans = min(ans, num)
    }
    println(ans)
}

// Tools
fun readString() = readLine()!!
fun readInt() = readLine()!!.toInt()
fun readLong() = readLine()!!.toLong()
fun readStringList() = readLine()!!.split(" ")
fun readIntList() = readLine()!!.split(" ").map(String::toInt)