Given a complete graph $G=(V,E)$. The "intracost" of $A\subset V(G)$ is defined by the total weight of all edges with both ends in $A$.
Given a complete graph $G=(V,E)$, where $|V(G)|=100$. Every edge has nonzero weight. Find a partition $(A,B)$ such that $|A|=|B|=50$ and the sum of intracost of $A$ and the intracost of $B$ is minimum.
I tried to start with finding a minimum cost perfect matching, but have no idea what to do next.