import kotlin.math.ceil

fun main() {
    val (n, f) = readInts()
    val a = readInts().map { it / 1000.0 }
    val all = buildList {
        for (i in a) {
            var j = 1
            while (i / j >= 1.0 / f) {
                add(i / j)
                j++
            }
        }
        add(1.0 / f)
        sortDescending()
    }
    println(all.withIndex().minOf { it.value * (it.index + n) })
}

private fun readInt() = readln().toInt()
private fun readLongs() = readStrings().map { it.toLong() }
private fun readStrings() = readln().split(" ")
private fun readInts() = readStrings().map { it.toInt() }