class List {
    public void add(){

    }
    public int get() {

    }
}

class Stack extends List{
    @Override
    public void add() {
        super.add();
    }

    @Override
    public int get() {
        return super.get();
    }
}

public class LSP {
    public static void main(String[] args) {
        List list = new List();
        Stack stack = new Stack();
        List myList = new Stack();
    }
}