I have XML contained in a string which has many invalid xml tags for an element, where a tag is "invalid" if it starts with a number. For example, the following are invalid:

```
 <1>....</1>, <123abc>, etc. 

```

In XML, we'd identify certain tags as invalid:

```
 <tag1> ----> valid tag
     <1tagname>....</1tagname> --->invalid tagname
     <2tagname>....</2tagname> --->invalid tag name
 </tag1> ----> valid tag

```

I want to fetch a list of invalid xml tags and I want to add a special string as a prefix let's say "item" so as to convert invalid to valid tag name.

I am using Java language compatiable regex.