#R. JIXMPII5Xzl3Wg#,>;:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ \ ] ^ _ ` a b c d e f g h i j k l m n

传统题

2000ms

256MiB

该比赛已结束，您无法在比赛模式下递交该题目。您可以点击“在题库中打开”以普通模式查看和递交本题。

Statement

Array of integers is unimodal, if:

it is strictly increasing in the beginning;
after that it is constant;
after that it is strictly decreasing.

The first block (increasing) and the last block (decreasing) may be absent. It is allowed that both of this blocks are absent.

For example, the following three arrays are unimodal: $[5,7,11,11,2,1]$ , $[4,4,2]$ , $[7]$ , but the following three are not unimodal: $[5,5,6,6,1]$ , $[1,2,1,2]$ , $[4,5,5,6]$ .

Write a program that checks if an array is unimodal.

Format

Input

The first line contains integer $n$ ( $1<=n<=100$ ) — the number of elements in the array.

The second line contains $n$ integers $a_{1},a_{2},...,a_{n}$ ( $1<=a_{i}<=1000$ ) — the elements of the array.

Output

Print "YES" if the given array is unimodal. Otherwise, print "NO".

Sample

6
1 5 5 5 4 2

YES

5
10 20 30 20 10

YES

4
1 2 1 2

NO

7
3 3 3 3 3 3 3

YES

ShanghaiTech ACM 炸鱼杯

未参加

状态: 已结束
规则: OI
题目: 46
开始于: 2024-12-10 23:00
结束于: 2024-12-15 13:00
持续时间: 110 小时
主持人: _Arahc_
参赛人数: 112

#R. JIXMPII5Xzl3Wg#,>;:

JIXMPII5Xzl3Wg#,>;:

Statement

Format

Input

Output

Sample

ShanghaiTech ACM 炸鱼杯

状态

开发

支持

#R. JIXMPII5Xzl3Wg#,>;:

JIXMPII5Xzl3Wg#,>;:

Statement

Format

Input

Output

Sample

ShanghaiTech ACM 炸鱼杯

状态

开发

支持

还没有账户？

登录