Given a permutation of the integers ~1~ to ~N~, print out the number of inversions in the array.
An inversion is defined as a pair of indices, ~i, j~ such that ~i \neq j, i < j, a_i > a_j~.
The first line will contain the integer ~N~ ~(1 \le N \le 10^5)~.
The second line will contain ~N~ integers, ~a_1, a_2, \ldots a_N~ ~(1 \le a_i \le N)~.
It is guaranteed the second line will contain a valid permutation of the integers from ~1~ to ~N~.
Output the number of inversions in the permutation.
4 3 2 1 4