Problem Description

Output the number of swaps that occur when the sequence $a$ is sorted using bubble sort.

Input Format

None

Output Format

None

Sample Input and Output

Sample Input #1

5
3 1 5 4 2

Sample Output #1

5

Sample Input #2

6
1 2 3 4 5 6

Sample Output #2

0

Sample Input #3

7
7 6 5 4 3 2 1

Sample Output #3

21

Sample Input #4

20
19 11 10 7 8 9 17 18 20 4 3 15 16 1 5 14 6 2 13 12

Sample Output #4

114

Notes/Hints

Constraints

• $1 \leq N \leq 100,000$

见题面 Input 部分

见题面 Output 部分