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ZOJ Problem Set - 4024
Peak

Time Limit: 1 Second      Memory Limit: 65536 KB

A sequence of $n$ integers $a_1, a_2, \dots, a_n$ is called a peak, if and only if there exists exactly one integer $k$ such that $1 < k < n$, and $a_i < a_{i+1}$ for all $1 \le i < k$, and $a_{i-1} > a_i$ for all $k < i \le n$.

Given an integer sequence, please tell us if it's a peak or not.

#### Input

There are multiple test cases. The first line of the input contains an integer $T$, indicating the number of test cases. For each test case:

The first line contains an integer $n$ ($3 \le n \le 10^5$), indicating the length of the sequence.

The second line contains $n$ integers $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 2 \times 10^9$), indicating the integer sequence.

It's guaranteed that the sum of $n$ in all test cases won't exceed $10^6$.

#### Output

For each test case output one line. If the given integer sequence is a peak, output "Yes" (without quotes), otherwise output "No" (without quotes).

#### Sample Input

7
5
1 5 7 3 2
5
1 2 1 2 1
4
1 2 3 4
4
4 3 2 1
3
1 2 1
3
2 1 2
5
1 2 3 1 2


#### Sample Output

Yes
No
No
No
Yes
No
No


Author: WENG, Caizhi
Source: The 15th Zhejiang Provincial Collegiate Programming Contest Sponsored by TuSimple
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