对角线 - 問題

#912. 对角线

統計

この問題は以下のコンテストで使用されています：

Elegia's Forgotten Hill

This problem is prepared by Elegia .

小艾给小兰出了一道题：一个 $n\times n$ 的方格，每个格子放一个 $1\sim c$ 的整数，有多少种方案使得任何一行有至少两种数出现，任何一列至少有两种数出现？

刚学过数数的小兰随便推了推，就解决了这个问题。

于是小艾加大了难度：如果 $i=j$ 这条对角线上的数都必须是 $1$，又有多少种方案？

请你帮小兰算一算，答案对 $998244353$ 取模。

输入格式

一行输入两个正整数 $n,c$，如题意所示。

输出格式

输出一个数，表示方案数对 $998244353$ 取模的结果。

样例数据

样例 1 输入

2 3

样例 1 输出

样例 2 输入

3 3

样例 2 输出

样例 3 输入

5 2

样例 3 输出

子任务

对于 $100\%$ 的数据，保证 $2\le n\le 10^6, 2\le c\le 10^8$。

数据点	$1,2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$	$10$
$n=$	$2$	$5$	$50$	$200$	$500$	$2000$	$5000$	$10^5$	$10^6$

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