Simplify exponential expression



Hi, just a simple question; how can I simplify exponential sum 

(%i01)v:(vin/(s*R)+v0*C)/(1/R+s*C+(1/(R+1/(s*C))))$
(%i02)[vin,v0,R,C]:[12,6,1,1]$
(%i03)ev(ratsimp(v))$
(%i04)ilt(%,s,t),exponentialize,expand;

to group  the first and the second term as well as the third and fourth  of the 
result, to get only two exponential terms plus a constant.

Thanks

Regards
Dionisio