Counting XML nodes

1

Some basic stuff with XML and not finding what I need online. Help appreciated.

What actionscript code will be able to determine these numerals for me and assign them to variables?

I want 1 variable to tell me how many firstChild(s?) there are <inventors>
Another variable to tell me how many children each firstChild(?) has, <person>
And another variable to tell me how many children each <person> has (name & comment)

Forgive me if my terminology is off, I feel like a dolt. If it’s not clear let me know. But I can’t figure out what code will do this. Thank so much

<?xml version="1.0"?>

<list>
<inventors>
    <person>
        <name>Thomas Edison</name>
        <comment>Inventor of many things...</comment>
    </person>
    <person>
        <name>Doug Engelbart</name>
        <comment>Invented the mouse...</comment>
    </person>
</inventors>

<inventors>
    <person>
        <name>Thomas Edison</name>
        <comment>Inventor of many things...</comment>
    </person>
</inventors>

<inventors>
    <person>
        <name>Thomas Edison</name>
        <comment>Inventor of many things...</comment>
    </person>
    <person>
        <name>Doug Engelbart</name>
        <comment>Invented the mouse...</comment>
    </person>
</inventors>

</list>