Convert varying xml to another xml

I have an input xml which looks like

<Root>
 <Monday>Monday<Monday>
 <Indicator>true<Indicator>
 <Value>1<Value>
 <Tuesday>Tuesday<Tuesday>
 <Indicator>true<Indicator>
 <Value>2<Value>
 <Wednesday>Wednesday<Wednesday>
 <Indicator>true<Indicator>
 <Value>3<Value>
</Root>

must be converted to the output xml which is

<Root>
 <Monday>Monday<Monday>
 <Value>1<Value>
 <Tuesday>Tuesday<Tuesday>
 <Value>2<Value>
 <Wednesday>Wednesday<Wednesday>
 <Value>3<Value>
</Root>

but the problem is the input xml can vary..sometimes it might be

<Root>
 <Monday>Monday<Monday>
 <Indicator>true<Indicator>
 <Value>1<Value>
 <Thursday>Thursday<Thursday>
 <Indicator>true<Indicator>
 <Value>4<Value>
</Root>

now the output must be

<Root>
 <Monday>Monday<Monday>
 <Value>1<Value>
 <Thursday>Thursday<Thursday>
 <Value>4<Value>
</Root>

And also I have the list of valid tags like Monday,Tuesday etc, which can come in the input xml in an arraylist in java.Any ideas on how to accomplish this.