Chemistry Intro

This song is awesome but i havent 
figured it out yet only the intro so
 here it is:

tuning(D,A,F,C,G,D)

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  D|--19----20----19----16-----|| 
  A|----17----17----17----17---|| 
  F|------16----16----16----20-|| 
  C|---------------------------|| 
  G|---------------------------|| 
  D|---------------------------|| 

 | x2 
 |    
 |    
 |    
 |    
 |    

  D|--18----19----18----15-----|--
  A|----16----16----16----15---|--
  F|------15----15----15----19-|--
  C|---------------------------|--
  G|---------------------------|--
  D|---------------------------|--

 |18----19----18----15-----|| 
 |--16----16----16----13---|| 
 |----15----15----15----12-|| 
 |-------------------------|| 
 |-------------------------|| 
 |-------------------------|| 

the second part might be wrong cause
 im writing this without my guitar 
in front of me
but ill fix it if i find it wrong.