I want to get a count value of set from list having specific property
Thanks in advance

```
class User(val age = 0, val group = "school")

fun main(
    val list = listof(User(1, "school"), User(2, "school"), User(3, "company"))

    fun getCount() {
        //how to get 2 (the count of set such as ("school", "company").size)
    }
}

```