Problem Statement
Given are integers $N$ and $M$. Find the number of integer sequences $a=(a_1,a_2,\cdots,a_N)$ that can be generated as follows, modulo $998244353$.
- Provide an undirected connected graph
$G$with$N$vertices and$M$edges. Here,$G$may not contain self-loops, but may contain multi-edges. - Perform DFS on
$G$and let$a_i$be the degree of the$i$-th vertex to be visited. More accurately, execute the pseudo-code below to get$a$.
a = empty array
dfs(v):
visited[v]=True
a.append(degree[v])
for u in g[v]:
if not visited[u]:
dfs(u)
dfs(arbitrary root)
Here, the variable $g$ represents the graph $G$ as an adjacency list, where $g[v]$ is the list of vertices adjacent to the vertex $v$ in arbitrary order.
For example, when $N=4,M=5$, it is possible to generate $a=(2,4,1,3)$, by providing the graph $G$ as follows.

Here, the numbers written on vertices represent the order they are visited in the DFS. (The DFS starts at the vertex labeled $1$.) The orange arrows show the transitions in the DFS, and the numbers next to them represent the order the edges are traversed.
Constraints
$2 \leq N \leq M \leq 10^6$- All values in input are integers.
Input
Input is given from Standard Input in the following format:
N M
Output
Print the answer.
样例
2 2
1
3 4
9
10 20
186225754
100000 1000000
191021899
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。