Selecting the value from diff i/p XML

Hello All,

I have two XML docs
Root1.xml and Root2.xml

==============================
Root1.xml looks like this
<root1>
        <item id="1" value="A"/>
        <item id="21" value="B"/>
        <item id="3" value="C"/>
        <item id="45" value="D"/>
        <item id="5" value="E"/>
        <item id="6" value="F"/>
        <item id="78" value="G"/>
        <item id="8" value="H"/>
        <item id="9" value="I"/>
        <item id="10" value="J"/>
</root1>

==================================
Root2.XML looks like this

<root2>
    <data id="1"/>
    <data id="2"/>
    <data id="3"/>
    <data id="4"/>
    <data id="5"/>
    <data id="6"/>
    <data id="7"/>
    <data id="8"/>
    <data id="9"/>
    <data id="10"/>
    <data id="11"/>
    <data id="2"/>
 </root2>
===================================

I want the compare the @id of both the <item> and <data> and when it matches I
want the value of the @value.
so for in this case my output would be

A
C
E
F
H
I
J
========================================
I wrote this XSLT
  
<xsl:key name="idlist" match="root2/data" use="@id"/>
<xsl:variable name="data" select="document('Root1.xml')"/>
<xsl:template match="/">
     <xsl:for-each select="key('idlist', $data/root1/item/@id)">
     <xsl:value-of select="@id"/>
     <br/>
     </xsl:for-each>
</xsl:template>

and
I am getting this output

1
3
5
6
8
9
10
By applying this XSLT on Root2.xml I am able to print the @id of <data>
element. But how to get the @value of <item> element from Root1.xml.
I always want to apply my XSLT on Root2.xml 

Thanks,
Shashank jain