题目描述

gshfd1jkhaRaadfglkjerVcvuy0gf said Prof. Pang.

To understand Prof. Pang's word, we would like to calculate the number of $\textit{namomo subsequence}$s of it. The word by Prof. Pang is a string $s$ with $n$ characters where each character is either an English letter (lower or upper case) or a digit. The $i$-th character of $s$ is denoted by $s[i]$ ($1\le i\le n$). A subsequence $t$ of $s$ is defined by a list of indices $t_1, \ldots, t_6$ such that $1\le t_1 < t_2 < \ldots < t_6\le n$. Let $compare(c_1, c_2)$ be a function on two characters such that $compare(c_1, c_2)=1$ when $c_1=c_2$ and $compare(c_1, c_2)=0$ otherwise. $t$ is a namomo subsequence of $s$ if and only if for any $1\le i<j\le 6$, $compare(s[t_i], s[t_j]) = compare(namomo[i], namomo[j])$, where $namomo[x]$ represents the $x$-th character of the string namomo ($1\le x\le 6$).

Output the number of namomo subsequences of a given string $s$ modulo $998244353$.

输入格式

The first line contains a string $s$ with $n$ characters ($6\le n\le 1000000$). $s$ contains only lower case English letters (a -- z), upper case English letters (A -- Z) and digits (0 -- 9).

输出格式

Output one integer -- the answer modulo $998244353$.

题目大意

给你一个串 $s$，问你有多少个长度为 $6$ 且形如 $A B C D C D$ 的子序列。

$6\le |s|\le 10^6$，字符集大小 $62$。

wohaha

1

momomo

0

gshfd1jkhaRaadfglkjerVcvuy0gf

73

retiredMiFaFa0v0

33