This plays at beginning of song.
e 6-6-6------------------------|
A ------5-5-5-5-----3--22-3-55-|
D -----------------------------|
G -----------------------------|
B -----------------------------|
E -----------------------------|
[ Tab from: http://www.guitaretab.com/b/bruno-mars/279245.html ]
Main track
e ---6--8--10-----6---8---10--8---6-6--8--6----6-6--8--10--8-8--11-10--6-8-5-|
A 5-5---------5-5---------------------------5--------------------------------|
D ---------------------------------------------------------------------------|
G ---------------------------------------------------------------------------|
B ---------------------------------------------------------------------------|
E ---------------------------------------------------------------------------|