summing, ok

Thanks Mukul Gandhi, 
 the stage 1 from summing  used  by exemplification - cars. It's all ok, cool.
thanks

Going on,  based in the same question,  how  must do I to proceed to
group a tag and totalize itself.

Using the same example:

<cars> 
   <car>
		<model>V667320</model>
		<name>Sportage</name>
                <categ>sport</categ>

   </car>
   <car>
		<model>M382932</model>
		<name>Silverado</name>
               <categ>pick-up</categ>
 </car>

Imagine that the first element (model) be written five times, the
second model two times, and other  any model  four times. Supposing
that this could be a greatest structure with 25 models and many
occurences to it , how to do to generate the total number of models
and not  occurences

The Total number  to display =  25 

if  consider the three , then  = 3   and  not    5+2+4

 
Marcos Hercules dos Santos