시간 제한메모리 제한제출정답맞힌 사람정답 비율
1 초 (추가 시간 없음) 1024 MB (추가 메모리 없음)1801129769.286%

문제

길이가 $n$인 수열 $(s_1,s_2,\ldots ,s_n)$이 주어진다. 함수 $f$는 다음과 같이 정의된다.

\[f(i,j,k) =\begin{cases}1&\text{if } s_{i+t}\leq s_{j+t}\text{ for all } 0\leq t<k\\ 0&\text{otherwise}\end{cases}\]

$\sum_{i=1}^{n}\sum_{j=1}^{n}\sum_{k=1}^{\min(n-i+1,n-j+1)}f(i,j,k)$의 값을 출력하라.

입력

첫 번째 줄에 수열의 길이를 나타내는 정수 $n$이 주어진다.

두 번째 줄에 $n$개의 정수 $s_1,s_2,\ldots ,s_n$이 공백으로 구분되어 주어진다.

출력

$\sum_{i=1}^{n}\sum_{j=1}^{n}\sum_{k=1}^{\min(n-i+1,n-j+1)}f(i,j,k)$의 값을 출력한다.

제한

  • $1\leq n\leq 5\, 000$
  • $1\le s_x\le 10^9$ ($1\le x\le n$)

서브태스크

번호배점제한
18

$1\leq n \leq 500$

292

추가적인 제약 조건이 없다.

예제 입력 1

2
2 3

예제 출력 1

4

예제 입력 2

5
2 4 2 2 1

예제 출력 2

35

노트

첫 번째 예제에 대한 설명은 다음과 같다.

  • $f(1,1,1) =1$
  • $f(1,1,2) =1$
  • $f(1,2,1) =1$
  • $f(2,1,1) =0$
  • $f(2,2,1) =1$
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채점 및 기타 정보

  • 예제는 채점하지 않는다.