A stream of n signed measurements is given. A pair of positions (i, j) with i < j is an anomaly when value[i] > 2 * value[j]. Count how many anomaly pairs exist.
Input format
Line 1: an integer n.
Line 2: n space-separated integers, the measurements.
Output format
A single integer: the number of anomaly pairs.
Constraints
- 1 ≤ n ≤ 100000
- -1000000000 ≤ value ≤ 1000000000