Parking

Source: Kattis

Version: Phuoc Hung OJ Extended

Problem Statement

A street is represented by an integer number line. Michael must visit $n$ stores, and store $i$ is at integer position $x_i$. He parks his car at one position and must return to the car after visiting all stores.

Compute the minimum total walking distance needed to visit all stores and return to the parked car.

Input

• The first line contains an integer $n$, the number of stores.
• The second line contains $n$ integers $x_0,x_1,\ldots,x_{n-1}$, the store positions.

Output

Print one integer, the minimum walking distance.

Subtasks

Subtask 1 (100 points): $1\le n\le20$ and $0\le x_i\le99$.

Examples

Input

4
24 13 89 37

Output

152

Explanation

The leftmost store is at $13$ and the rightmost at $89$. Visiting all stores and returning to the car requires covering the interval of length $89-13=76$ in both directions, so the minimum distance is $2\cdot76=152$.