$]$ Let Double$-$CLIQUE denote the following language:

n

$$G$,$ k$$ : G is an undirected graph and k is an integer

such that G has two disjoint cliques each of size at least k

o

$.$

Here two cliques are said to be disjoint if they don$$t share any vertices. Prove that

Double$-$CLIQUE is NP$-$complete. $($Hint: Reduce from CLIQUE.$)$