#761. Number of inversions
Count the pairs with i < j and a[i] > a[j].
### Input
The first line has n, the second line has n integers separated by spaces.
### Output
A number.
Examples
Input
13 20 0 1 15 17 9 19 2 0 19 20 0 7
Output
37
Input
11 16 12 5 11 10 1 4 6 18 18 19
Output
22
💡 You can solve it with Python, JavaScript or blocks. Read the input line by line with input(). Don't print a question (like input("Number: ")). Print exactly what the output asks for, nothing more.