Run For Your Prize

题意翻译

在一条线上，你1处，朋友在$10^6$处，你们两中间有n个礼物第i个礼物坐标为$a_i$ ($1<a_i<10^6$ )你们两个的速度为1，,被经过的礼物就被认为是捡起的，你们想把所有礼物捡起，问最少要多少秒。

题目描述

You and your friend are participating in a TV show "Run For Your Prize". At the start of the show $ n $ prizes are located on a straight line. $ i $ -th prize is located at position $ a_{i} $ . Positions of all prizes are distinct. You start at position $ 1 $ , your friend — at position $ 10^{6} $ (and there is no prize in any of these two positions). You have to work as a team and collect all prizes in minimum possible time, in any order. You know that it takes exactly $ 1 $ second to move from position $ x $ to position $ x+1 $ or $ x-1 $ , both for you and your friend. You also have trained enough to instantly pick up any prize, if its position is equal to your current position (and the same is true for your friend). Carrying prizes does not affect your speed (or your friend's speed) at all. Now you may discuss your strategy with your friend and decide who will pick up each prize. Remember that every prize must be picked up, either by you or by your friend. What is the minimum number of seconds it will take to pick up all the prizes?

输入输出格式

输入格式

The first line contains one integer $ n $ ( $ 1<=n<=10^{5} $ ) — the number of prizes. The second line contains $ n $ integers $ a_{1} $ , $ a_{2} $ , ..., $ a_{n} $ ( $ 2<=a_{i}<=10^{6}-1 $ ) — the positions of the prizes. No two prizes are located at the same position. Positions are given in ascending order.

输出格式

Print one integer — the minimum number of seconds it will take to collect all prizes.

输入输出样例

输入样例 #1

3
2 3 9

输出样例 #1

8

输入样例 #2

2
2 999995

输出样例 #2

5

说明

In the first example you take all the prizes: take the first at $ 1 $ , the second at $ 2 $ and the third at $ 8 $ . In the second example you take the first prize in $ 1 $ second and your friend takes the other in $ 5 $ seconds, you do this simultaneously, so the total time is $ 5 $ .