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Problems

Bubble sort

Bubble sort

Time limit 1 second
Memory limit 64 MiB

Determine how many exchange operations are done in bubble sort algorithm to sort the elements of array in ascending order.

Input data

The first line contains the number of elements n (1n1000) in array. The second line contains the array itself. It is guaranteed that all array elements are different and do not exceed 10^9 by absolute value.

Output data

Print the number of swaps in bubble sort.

Examples

Input example #1
3
1 3 2
Output example #1
1
Input example #2
2
2 1
Output example #2
1
Input example #3
4
4 1 5 3
Output example #3
3