P5258 [CF1817F] Entangled Substrings
NOI
题目描述

You are given a string $s$. A pair of its non-empty substrings $(a, b)$ is called entangled if there is a (possibly empty) link string $c$ such that:

  • Every occurrence of $a$ in $s$ is immediately followed by $cb$;
  • Every occurrence of $b$ in $s$ is immediately preceded by $ac$.

In other words, $a$ and $b$ occur in $s$ only as substrings of $acb$. Compute the total number of entangled pairs of substrings of $s$.

A string $a$ is a substring of a string $b$ if $a$ can be obtained from $b$ by the deletion of several (possibly zero or all) characters from the beginning and several (possibly zero or all) characters from the end.

Input

The first and only line contains a string $s$ of lowercase English letters ($1 \leq |s| \leq 10^5$) — the string for which you should count pairs of entangled substrings.

Output

Output a single integer, the number of entangled pairs of substrings of $s$.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
abba
样例输出
1
提示

In the first example, the only entangled pair is (ab,ba). For this pair, the corresponding link string $c$ is empty, as they only occur as substrings of the whole string abba, which doesn't have any characters between ab and ba.

In the second example, there are no entangled pairs.

In the third example, the entangled pairs are (a,b), (b,c), (a,c), (a,bc), and (ab,c). For most pairs, the corresponding link string $c$ is empty, except for the pair (a,c), for which the link string $c$ is b, as a and c only occur as substrings of the string abc.