/**
 * You can edit, run, and share this code.
 * play.kotlinlang.org
 */
fun main() {
    val numbers = listOf(1,2,3,4)
    
    var numSet: MutableSet<Int> = mutableSetOf()
    
    for (number in numbers) {
        numSet.add(number)
    }
    
    println(numSet.size == numbers.size)
    
}