how to remove empty tag from output xml using for-each loop in xslt?

input xml:

<sb:pages>

   <sb:first-page>

     461

   </sb:first-page>

   <sb:last-page>

     70

   </sb:last-page>

</sb:pages> 

<sb:pages>

   <sb:first-page>

     461

  </sb:first-page>

</sb:pages> 

my output xml:

<sb:pages>

   <sb:first-page>461</sb:first-page>

   <sb:last-page>70</sb:last-page>

</sb:pages> 

<sb:pages>

   <sb:first-page>461</sb:first-page>

   <sb:last-page/>

</sb:pages> 

i dont want second last-page in my output xml. because sb:pages[last()]/sb:last-page is not in my input xml. i am using for-each loop in my xslt. what i have to do to get the output xml without empty tag?

My expected output xml is:

<sb:pages>

   <sb:first-page>461</sb:first-page>

   <sb:last-page>70</sb:last-page>

</sb:pages> 

<sb:pages>

   <sb:first-page>461</sb:first-page>

</sb:pages> 

anyone help me to solve this problem?