convert file

[scialom]

Hi,

I have this txt file:

<SYNC Start=35973040>
<P Class=AFCC><Div Style="text-align: center;font-family: arial, sans-serif;font-size: 12pt;margin-left: 8pt;margin-right: 8pt;">Lon Chaney doit son charme</Div>
<Div Style="text-align: center;font-family: arial, sans-serif;font-size: 12pt;margin-left: 8pt;margin-right: 8pt;">à son visage ridé,</Div>
<SYNC Start=35976080>
<P Class=AFCC> &nbsp;
<SYNC Start=35976240>
<P Class=AFCC><Div Style="text-align: center;font-family: arial, sans-serif;font-size: 12pt;margin-left: 8pt;margin-right: 8pt;"></Div>

etc...

I need to recalculate the start number - to take the first number 35973040 and set it for 0 the the second number will be: 35976080-35973040=?

etc...
then in the end to save it as a new file. How can I do it?

Thanks,
Assaf