A.kt

import java.lang.AssertionError


private val input = System.`in`.bufferedReader()
private val output = StringBuilder()


private fun readLn() = input.readLine()!! // string line
private fun readInt() = readLn().toInt() // single int
private fun readLong() = readLn().toLong() // single long
private fun readDouble() = readLn().toDouble() // single double
private fun readStrings() = readLn().split(" ") // list of strings
private fun readInts() = readStrings().map { it.toInt() } // list of ints
private fun readLongs() = readStrings().map { it.toLong() } // list of longs
private fun readDoubles() = readStrings().map { it.toDouble() } // list of doubles

private fun myAssert(x: Boolean) {
    if (!x) {
        throw AssertionError()
    }
}

private fun runCase() {

    var n = readInt()
    var a = readLongs()
    a = a.sorted()
    var ans: Long = 0L
    for(i in 0 until n) {
        ans = maxOf(ans, a[i] * (n - i))
    }
    output.append("$ans\n")
}


fun main(args: Array<String>) {

    var t: Int = 1
    t = readInt()
    repeat(t) {
        runCase()
    }

    print(output)
}