题目描述
Problem Statement
Given is a sequence of integers $A = (A_1, \ldots, A_N)$.
Consider a pair of sequences of integers $B = (B_1, \ldots, B_N)$ and $C = (C_1, \ldots, C_N)$ that satisfies the following conditions:
- A_i = B_i + C_i holds for each $1\leq i\leq N$;
- B is non-decreasing, that is$, B_i\leq B_{i+1}$ holds for each $1\leq i\leq N-1$;
- C is non-increasing, that is$, C_i\geq C_{i+1}$ holds for each $1\leq i\leq N-1$.
Find the minimum possible value of $\sum_{i=1}^N \bigl(\lvert B_i\rvert + \lvert C_i\rvert\bigr)$.
Input
Input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_N$
Output
Print the answer.
Constraints
- $1\leq N\leq 2\times 10^5$
- -$10^8\leq A_i\leq 10^8$
Sample Input 1
3
1 -2 3
Sample Output 1
10
One pair of sequences $B = (B_1, \ldots, B_N)$ and $C = (C_1, \ldots, C_N)$ that yields the minimum value is:
- B = (0, 0, 5),
- C = (1, -2, -2).
Here we have $\sum_{i=1}^N \bigl(\lvert B_i\rvert + \lvert C_i\rvert\bigr) = (0+1) + (0+2) + (5+2) = 10$.
Sample Input 2
4
5 4 3 5
Sample Output 2
17
One pair of sequences B and C that yields the minimum value is:
- B = (0, 1, 2, 4),
- C = (5, 3, 1, 1).
Sample Input 3
1
-10
Sample Output 3
10
One pair of sequences B and C that yields the minimum value is:
- B = (-3),
- C = (-7).
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分