How to charge 18650 li-ion cells connected in series

I have four 18650 li-ion 3.7 volt batteries connected in series (gives almost 14.8 to 15 volt together). My question is how could i charge them in series. I have two laptop chargers, One is 13 volt 2A and the other is 19volt 4.7Amp.

With a Li series charger.

Try a search on "li series charger module"