How to call a different super from primary constructor in secondary constructor

Support
1 
open class a(val string: String) {
    constructor(string: String, int: Int) : this(string)
}

class b(string: String): a(string) {
    constructor(string: String, int: Int) : super(string, int)
}

As title, how can I achieve this?

2

Ok, I found out that is not using primary constructor