data in Sender Mail Adaptor - Subject line

Hi Experts,

We have requirement like Sender Mail Adapter in Subject line (field) the data is coming like "Enquiry for Purchase Order Number 5**********(10digit) OR "Enquiry for Vendor Number 3**** (5digit).

5*********(10digit) PO is mapped with EBELN

3**** (5digit) Vendor is mapped with  LIFNR

Which logic to read only numeric value from field ?

Also what logic to read 10 digit & 5 digit respectively .

Kindly advise?

Thanks..