fun readInts() = readLine()!!.split(' ').map(String::toInt)

fun main(args: Array<String>) {
    val (d, g) = readInts()
    val pp = IntArray(d)
    val cc = IntArray(d);
    for (i in 0 until d) {
        val (p, c) = readInts()
        pp[i] = p
        cc[i] = c
    }
    var ans = Int.MAX_VALUE
    root@for (i in 0 until (1 shl d)) {
        var solved = 0
        var score = 0
        for (j in 0 until d) {
            if (i and (1 shl j) == 0) continue
            solved += pp[j]
            score += 100 * (j + 1) * pp[j] + cc[j]
        }
        if (g <= score) {
            ans = Math.min(ans, solved)
            continue
        }
        for (j in d - 1 downTo 0) {
            if (i and (1 shl j) != 0) continue
            for (k in 0 until pp[j]) {
                solved++
                score += 100 * (j + 1)
                if (g <= score) {
                    ans = Math.min(ans, solved)
                    continue@root
                }
            }
        }
    }
    println(ans)
}
