C# xml parser for non-noded value [duplicate]

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• Reading XML comments in C# 6 answers

How can i parse this RUID: [value] value from xml, any ideas

<response>
</response>
<!-- RUID: [UmFuZG9tSVYkc2RlIyh9YQGcRIMHryJSA8r+sODrfrI11L6d1gSdXeQIWR+JUqw7jiueqxiOEPqYAFoNTD2eUQ==] -->

I'm not pretty shore about some like this:

        int first = ruid.IndexOf("RUID: [") + count;
        int last = ruid.LastIndexOf("] -->");
        ruid = ruid.Substring(first, last - first); 

Please give me some another way