- Time limit: 1.00 s
- Memory limit: 512 MB
Maija is sorting her book shelf by the books' ID numbers. She keeps repeating the same operation until the shelf is sorted: she picks two adjacent books where the left one's ID is greater than the right one's and swaps them. It can be proven that the books will be sorted after a finite number of moves like this. Calculate the minimum number of moves it takes to sort n books when the i-th one's ID is a_i.
Input
The first line contains an integer n. The second line contains n integers a_1,\,a_2,\ldots,\,a_n.
Output
Print the minimum number of moves required to sort the books.
Constraints
- 1 \leq n \leq 2 \times 10^5
- 1 \leq a_i \leq 10^9
Example 1
Input:
5 6 1 8 9 3
Output:
4
Example 2
Input:
10 6 1 8 9 3 2 6 6 9 5
Output:
18
Example 3
Input:
1 1000000000
Output:
0