How to tag the paragraph indent level using c#

Sorry guys, i was in hurry, so i coudlnt  explain fully,

i want to tag the " book index" like

the " book index" like

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INDEX
AC (Advance Audio Coding), 5, 15
Automated Self-Optimization of Cellular Networks, 144
Automatic frequency planning. See AFP
Automatic neighbor relation. See ANR

Backup service coverage, 193–4, 196
BAL (BCCH Allocation List), 114, 213
Balancing, 23, 25, 43, 115, 156, 169, 173, 175, 184, 186–91, 217

 techniques, 188, 250, 255

 differential, 233–4, 236, 243, 248, 251

 procedure, 76, 177–8

 requests, 171–2

Band, 11–13, 99, 191–3, 213
Bandwidth, 8, 13, 81, 94, 97–8, 100, 181–2
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i just want to find the indent level using c# coding, also i want tag the index like this


 AC (Advance Audio Coding), 5, 15
 Automatic frequency planning. See AFP
 Automatic frequency planning. See AFP
 


 Backup service coverage, 193–4, 196
 BAL (BCCH Allocation List), 114, 213
 

  techniques, 188, 250, 255

 

  differential, 233–4, 236, 243, 248, 251

  procedure, 76, 177–8

  requests, 171–2

 
 
 Band, 11–13, 99, 191–3, 213
 Bandwidth, 8, 13, 81, 94, 97–8, 100, 181–2
 




the first grouping end with enter mark. i want group the index using their indent level, pleaseguide me to do this  process please