[Kotlin] I/O readline

import java.util.*

fun main(args: Array<String>) {
    val number = Random().nextInt(100) + 1
    
    var input: String?
    var guess = -1
    
    while(guess!=number) {
        print("Guess a number between 1 and 100: ")
        
        input = readLine()
        
        if(input != null) {
            // can throw NumberFormatExpection
            guess = input.toInt()
        }
        
        if (guess < number) {
           println("Too low") 
        } else if (guess > number){
            println("Too large") 
        } else {
            println("correct!")
        }
    }
}