题目描述
A permutation of N numbers from 1 to N A1, A2, ……, AN is given. You can perform the operation reverse (i, j) to reverse the order of the numbers in the interval [i, j] (1 ≤ i ≤ j ≤ N) for this permutation. For example, if reverse (2, 4) is applied to [1, 2, 3, 4, 5], it becomes [1, 4, 3, 2, 5]. Calculate how many operations you need to do at a minimum to get the permutation sorted in ascending order.
Constraints
-
N is an integer
-
2 ≤ N ≤ 10
Input
The input is given in the following format.
N
A1 A2 …… AN
Output
Print the solution to the problem on one line.
Examples
Input
5
1 4 3 5 2
Output
2
Input
5
3 1 5 2 4
Output
4
Input
3
1 2 3
Output
0
Input
10
3 1 5 2 7 4 9 6 10 8
Output
9
输入格式
见题面
输出格式
见题面
样例输入
3
1 2 3
样例输出
0