What should come in place of the question mark (?) to complete the following letter series? F, E, I, G, L, I, O, ?

I J L K

K

F, E, I, G, L, I, O, ? In this there are two series : F ,  I , L , O AND E , G , I , ? we can get the answer with the help of  E , G , I , ? E + 2 = G G + 2 = I I + 2 = K