A group of n people are waiting in line at a store. Suddenly, the store decides to close the first counter and open a second counter instead. Everyone sees an opportunity to get served quickly and runs to the new counter so people change their positions in the line. People who flipped positions start to argue (I.e., if person A was ahead of person B earlier, and now person B is ahead of person A, then they start quarreling.), so the store decided that the best strategy is to expel the maximum number of people every pair of whom is arguing with one another. Can you help the store identify such a group of people in O(n^2) time? A) Describe your algorithm B) Running time C) Proof of correctness for algorithm