Number of inversions

Write a program that finds for a given array A = <a[1], a[2], ..., a[n]> the number of such pairs (i, j) that i < j and a[i] > a[j].

Input

The first line contains the number of array elements n (1 ≤ n ≤ 50000). Second line contains n different elements of array A - nonnegative integers, not greater than 10^6.

Output

Print the number of required pairs.

Examples