You are given a int permutation containing a permutation of the first n positive integers (1 through n), and you want to sort them in ascending order. To do this, you will perform a series of swaps. For each swap, you consider all pairs (i, j) such that i < j and permutation[i] > permutation[j]. Among all those pairs, you choose one randomly and swap permutation[i] and permutation[j]. Each pair has the same probability of being chosen. Return the expected number of swaps needed to sort permutation in ascending order.