[xsl] number of particular sub elements

["John Smith" <debrief@xxxxxxxxx>]

Hello,

how can I retrieve the number of children in the context node and set
it as variable, or the parameter?

instead of this:

<xsl:template name="aName">
	<xsl:param name="max" select="last()" />
...
</xsl:template>


I want to do something like this, (the code below is incorrect and
only serves as a mean to describe what I am trying to achive)


<xsl:template name="aName">
	<xsl:param name="max" select="particularSubElements.last()" />
....
</xsl:template>

so if the context node was 'x' I want to the number of 'y' sub elements:

<x>
    <z />
    <y />
    <z />
    <y />
    <z />
</x>

So want to get the number of 'y' elements which in this case is 2.

Thanks,
J