How to count the distinct values in the XML extract? for eText template.

Hi,

How do we count the distinct values in the particular node in XML for eText?

For e.g.

I have an extract that looks like..

<OutboundPayment>

     <BankAccount>

          <BankAccountNumber>1234</BankAccountNumber>

     </BankAccount>

     <BankAccount>

          <BankAccountNumber>5678</BankAccountNumber>

     </BankAccount>

     <BankAccount>

          <BankAccountNumber>1234</BankAccountNumber>

     </BankAccount>

</OutboundPayment>

Now, here I have a requirement to count number of distinct values under /OutboundPayment/BankAccount/BankAccountNumber/

How can I accomplish that? in eText?

Regards,

Aniket