import kotlin.math.min

fun main() = abc104c()

@OptIn(ExperimentalStdlibApi::class)
fun abc104c() = IO_abc104c().exec {
    val (n, targetScore) = readInt() to readLong()
    val pcList = Array(n) { readLong() to readLong() }.reversedArray()

    var answer = Long.MAX_VALUE

    // 0: not try, 1:partial try, 2:all try
    searchAllPatterns(arrayOf(0, 1, 2), n) { types ->
        var remainScore = targetScore
        var solveProblems = 0L
        types.withIndex().sortedByDescending { it.value }.forEach { (i, type) ->
            val (problems, completeBonus) = pcList[i]
            val point = (n - i) * 100
            when (type) {
                1 -> {
                    if (remainScore > 0) {
                        val solveProblem = min(problems, (remainScore + point - 1) / point)
                        solveProblems += solveProblem
                        remainScore -= solveProblem * point
                    }
                }
                2 -> {
                    solveProblems += problems
                    remainScore -= point * problems + completeBonus
                }
            }
        }
        if (remainScore <= 0) answer = min(answer, solveProblems)
    }

    println(answer)
}

@Suppress("SameParameterValue")
private inline fun <reified T> searchAllPatterns(patterns: Array<T>, length: Int, action: (Array<T>) -> Unit) {
    val patternSize = patterns.size
    val pow = (1..length).fold(1L) { acc: Long, _: Int -> acc * patternSize }
    val allPatterns = if (pow in 1..Int.MAX_VALUE) pow.toInt() else error("$pow is too large!")
    for (i in 0 until allPatterns) {
        val array = Array(length) { patterns[0] }
        var div = 1
        for (j in 0 until length) {
            array[length - j - 1] = patterns[(i / div) % patternSize]
            div *= patternSize
        }
        action(array)
    }
}

// region kokokara template dayo (^o^)
@Suppress("unused", "ClassName", "SpellCheckingInspection", "ConvertToStringTemplate", "MemberVisibilityCanBePrivate")
private class IO_abc104c(private val separator: String = System.lineSeparator()) {
    private val input = System.`in`
    private val buffer = ByteArray(1024)
    private var pointer = 0
    private var bufferLength = 0
    private val sb = StringBuilder()
    private fun Byte.isPrintable() = this in 33..126
    private fun Byte.isNumeric() = this in '0'.toByte()..'9'.toByte()
    private fun Byte.toNumVal() = if (this.isNumeric()) this - '0'.toByte() else error("$this is not numeric")

    private fun hasNextByte(): Boolean {
        return if (pointer < bufferLength) true else {
            pointer = 0
            bufferLength = input.read(buffer)
            bufferLength > 0
        }
    }

    private fun readByte(): Byte = if (hasNextByte()) buffer[pointer++] else -1
    private fun skipUnprintable() = run { while (hasNextByte() && !buffer[pointer].isPrintable()) pointer++ }
    private fun hasNext(): Boolean = run { skipUnprintable() }.run { hasNextByte() }
    private fun hasNextOrError() = if (!hasNext()) error("has no next element.") else Unit

    fun readString(): String {
        hasNextOrError()
        val sb = StringBuilder()
        var b = readByte()
        while (b.isPrintable()) {
            sb.appendCodePoint(b.toInt())
            b = readByte()
        }
        return sb.toString()
    }

    fun readLong(): Long {
        hasNextOrError()
        var n = 0L
        var negative = false
        var b = readByte()
        if (b == '-'.toByte()) {
            negative = true
            b = readByte()
        }
        if (!b.isNumeric()) error("$b is not numeric.")
        while (true) {
            when {
                b.isNumeric() -> n = n * 10 + b.toNumVal()
                b.toInt() == -1 || !b.isPrintable() -> return if (negative) -n else n
                else -> error("failed to parse. [n=$n, b=$b]")
            }
            b = readByte()
        }
    }

    fun readInt() = readLong()
        .let { if (it in Int.MIN_VALUE..Int.MAX_VALUE) it.toInt() else error("$it is not in range of Int.") }

    fun readDouble(): Double {
        var n = 0.0
        var div = 1.0
        var negative = false
        var b = readByte()
        if (b == '-'.toByte()) {
            negative = true
            b = readByte()
        }
        do n = n * 10 + b.toNumVal()
        while (run { b = readByte() }.run { b.isNumeric() })
        if (b == '.'.toByte()) {
            while (run { b = readByte() }.run { b.isNumeric() })
                n += b.toNumVal() / (run { div *= 10 }.run { div })
        }
        return if (negative) -n else n
    }

    fun println(): Unit = run { sb.append(separator) }
    fun print(any: Any): Unit = run { sb.append(any) }
    fun println(any: Any): Unit = run { sb.append(any.toString() + separator) }
    fun flush() = run { kotlin.io.println(sb); sb.clear() }

    fun exec(action: IO_abc104c.() -> Unit) {
        var t: Throwable? = null
        Thread(null, { action() }, "solve", 128 * 1024 * 1024)
            .apply { setUncaughtExceptionHandler { _, t1 -> t = t1 } }
            .apply { start() }.join()
        t?.let { throw it }
        kotlin.io.print(sb)
    }

    fun readLine(): Nothing = error("readLine is disabled.")
}
// endregion kokomade template dayo (^o^)


Measured memory_bytes: 58648