Smallest Substring - KOTLIN

import java.util.*

var sc: Scanner = Scanner(System.`in`)

fun main() {
    val n: Int = sc.nextInt()
    val s: String = sc.next()
    val res = smallestSubstring(n, s)
    println(res)
}

fun smallestSubstring(n: Int, s: String): Int {
    val temp: CharArray = s.toCharArray()

    // Check for length of 2
    for (i in 0 until n - 1) {
        if (temp[i] == 'x' && temp[i + 1] == 'x')
            return 2
    }

    // Check for length of 3
    for (i in 0 until n - 2) {
        if (temp[i] == 'x' && temp[i + 2] == 'x')
            return 3
    }

    // Check for length of 4
    for (i in 0 until n - 3) {
        if (temp[i] == 'x' && temp[i + 3] == 'x' && temp[i + 1] != temp[i + 2])
            return 4
    }

    // Check for length of 7
    for (i in 0 until n - 6) {
        if (temp[i] == 'x' && temp[i + 3] == 'x' && temp[i + 6] == 'x') {
            var countY = 0
            var countZ = 0
            for (j in i + 1..i + 5) {
                if (temp[j] == 'y')
                    countY++
                else if (temp[j] == 'z')
                    countZ++
            }
            if (countY == 2 && countZ == 2)
                return 7
        }
    }
    return -1
}