fun pickingNumbers(a: Array<Int>): Int {
    // Write your code here
    var maxLength = 1
    var maxValue = 0
    val frequencies = MutableList(100) { 0 }

    a.forEach { num ->
        maxValue = Math.max(num, maxValue)
        frequencies[num]++
    }

    for (i in 1..maxValue) {
        val subListLength = frequencies[i] + frequencies[i - 1]
        maxLength = Math.max(maxLength, subListLength)
    }

    return maxLength
}``