Graph G is isomorphic to its compliment. Proving degree characteristics. Help

Suppose that G is isomorphic with its compliment (I cant put the bar on top of G so let G compliment be denoted by **G**and that n=|V(G)|=4*k+1for some integer k>=1 (**G** is the complement of G). Suppose that the degree sequence of G is d_1>=d_2>=...>=d_n.

a) Prove that d_i+d_(n-i+1)=n-1 for each i=1,2,...n.

b) Use (a) to prove G has at least one vertex with degree (n-1)/2.

NOTE: this _ is meant to indicate a subscript hence d_(n-i+1) means the entire (n-i+1) is a subscript of d.

I am very stuck on how I got about proving part a and as a consequence part B. I can draw what happens and think I understand the premise BUT the prooof has me kuffafeld (Nerd).

Help would be utterly and forever appreciated.

THANK YOU!