elementary xml parser

reads and sorts the data from an xml file with the following structure:
<ocene>
  <ocena>
    <vpisnaStevilka>12345678</vpisnaStevilka> <!-- student ID = 8 chars -->
    <nalogaID>123</nalogaID><!-- excercise ID -->
    <vrednost>123</vrednost><!-- value of the excercise -->
  </ocena>
</ocene>