import kotlin.math.max


fun calMax(m: Int, current: Int, currentMax: Int, mods: IntArray): Int {
    if (m == mods.lastIndex) {
        return max(currentMax, current % mods.last())
    }
    if (current < currentMax) return currentMax
    return calMax(m + 1, current, calMax(m + 1, current % mods[m], currentMax, mods), mods)
}

fun main() {
    val (n, k) = readLine()!!.trim().split(' ').map(String::toInt)
    val mods = readLine()!!.trim().split(' ').map(String::toInt).sortedDescending().toIntArray()
    println(calMax(0, k, 0, mods))
}