题目描述

Welcome to the test,wish you can do well in this test.

So let's take a look at this question.

Zsh has an array $a$ of length $n$.Now he wants you to calculate $a[1]-\\sum_{i=2}^n a[i]$ (1 indexed).

输入格式

The first line contains an integer $n$ ($1 \\leq n \\leq 100000$) — the length of array $a$.

The second line contains $n$ integers $a_1,a_2,...,a_n$ ($-100000\\leq a_i \\leq 100000$) — the elements of the array $a$.

输出格式

Only the answer.

样例

4 
1 2 3 4

-8

2 
-1 -1

0