fun missingNumbers(arr: Array<Int>, brr: Array<Int>): List<Int> {
    val countMap = brr.groupingBy { it }.eachCount().toMutableMap()

    arr.forEach { y ->
        countMap[y]?.let { count ->
            if (count > 1) countMap[y] = count - 1 else countMap.remove(y)
        }
    }

    return countMap.keys.sorted()
}