CF1038D Slime

### 题目大意： 有$n$只史莱姆qwq，每只史莱姆有一个分数，每次一只史莱姆可以吞掉左边的或者右边的相邻史莱姆（要是有的话），然后ta的分数会减去被吞的史莱姆的分数，问最后剩下的史莱姆分数最大为多少

第一行一个整数$n$ 第二行$n$个整数，表示史莱姆的分数

一个整数，即最大分数

In the first example, a possible way of getting the last slime with value $ 4 $ is: - Second slime eats the third slime, the row now contains slimes $ 2, -1, 1 $ - Second slime eats the third slime, the row now contains slimes $ 2, -2 $ - First slime eats the second slime, the row now contains $ 4 $ In the second example, the first slime can keep eating slimes to its right to end up with a value of $ 4 $ .