import bisect import copy import decimal import fractions import functools import heapq import itertools import math import random import sys from collections import Counter,deque,defaultdict from functools import lru_cache,reduce from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max def _heappush_max(heap,item): heap.append(item) heapq._siftdown_max(heap, 0, len(heap)-1) def _heappushpop_max(heap, item): if heap and item < heap[0]: item, heap[0] = heap[0], item heapq._siftup_max(heap, 0) return item from math import degrees, gcd as GCD read=sys.stdin.read readline=sys.stdin.readline readlines=sys.stdin.readlines def Extended_Euclid(n,m): stack=[] while m: stack.append((n,m)) n,m=m,n%m if n>=0: x,y=1,0 else: x,y=-1,0 for i in range(len(stack)-1,-1,-1): n,m=stack[i] x,y=y,x-(n//m)*y return x,y class MOD: def __init__(self,p,e=1): self.p=p self.e=e self.mod=self.p**self.e def Pow(self,a,n): a%=self.mod if n>=0: return pow(a,n,self.mod) else: assert math.gcd(a,self.mod)==1 x=Extended_Euclid(a,self.mod)[0] return pow(x,-n,self.mod) def Build_Fact(self,N): assert N>=0 self.factorial=[1] self.cnt=[0]*(N+1) for i in range(1,N+1): ii=i self.cnt[i]=self.cnt[i-1] while ii%self.p==0: ii//=self.p self.cnt[i]+=1 self.factorial.append((self.factorial[-1]*ii)%self.mod) self.factorial_inve=[None]*(N+1) self.factorial_inve[-1]=self.Pow(self.factorial[-1],-1) for i in range(N-1,-1,-1): ii=i+1 while ii%self.p==0: ii//=self.p self.factorial_inve[i]=(self.factorial_inve[i+1]*ii)%self.mod def Fact(self,N): if N<0: return 0 return self.factorial[N]*pow(self.p,self.cnt[N],self.mod)%self.mod def Fact_Inve(self,N): if self.cnt[N]: return None return self.factorial_inve[N] def Comb(self,N,K,divisible_count=False): if K<0 or K>N: return 0 retu=self.factorial[N]*self.factorial_inve[K]*self.factorial_inve[N-K]%self.mod cnt=self.cnt[N]-self.cnt[N-K]-self.cnt[K] if divisible_count: return retu,cnt else: retu*=pow(self.p,cnt,self.mod) retu%=self.mod return retu def Zip(lst): unzip=sorted(list(set(lst))) zip={x:i for i,x in enumerate(unzip)} return zip,unzip class UnionFind: def __init__(self,n): self.n=n self.parents=[-1]*n def Find(self,x): stack=[] while self.parents[x]>=0: stack.append(x) x=self.parents[x] for y in stack: self.parents[y]=x return x def Union(self,x,y): x=self.Find(x) y=self.Find(y) if x==y: return if self.parents[x]>self.parents[y]: x,y=y,x self.parents[x]+=self.parents[y] self.parents[y]=x def Size(self,x): return -self.parents[self.Find(x)] def Same(self,x,y): return self.Find(x)==self.Find(y) def Members(self,x): root = self.Find(x) return [i for i in range(self.n) if self.Find(i)==root] def Roots(self): return [i for i, x in enumerate(self.parents) if x<0] def Group_Count(self): return len(self.Roots()) def All_Group_Members(self): group_members = defaultdict(list) for member in range(self.n): group_members[self.Find(member)].append(member) return group_members def __str__(self): return '\n'.join(f'{r}: {m}' for r, m in self.All_Group_Members().items()) N,M=map(int,readline().split()) edges=[] for _ in range(M): a,b=map(int,readline().split()) a-=1;b-=1 edges.append((a,b)) ans=0 mod=998244353 MD=MOD(mod) MD.Build_Fact(N) @lru_cache(maxsize=None) def f(n,c): s=0 if c>=2: s+=MD.Fact(c-1) elif n!=N-1: s+=1 for i in range(c+1,n+1): s+=MD.Comb(n-c,i-c)*MD.Fact(i-1) s%=mod s*=pow(2,c-1,mod) s%=mod return s for i in range(3,N+1): ans+=MD.Comb(N,i)*MD.Fact(i-1) ans%=mod ans*=MD.Pow(2,-1) ans%=mod for bit in range(1,1<>i&1: a,b=edges[i] points.append(a) points.append(b) pop_cnt+=1 zip,unzip=Zip(points) l=len(zip) UF=UnionFind(l) cnt=[0]*l cycle=False for i in range(N): if bit>>i&1: a,b=edges[i] UF.Union(zip[a],zip[b]) cnt[zip[a]]+=1 cnt[zip[b]]+=1 for c in cnt: if c>=3: continue if cnt.count(2)==l and UF.Group_Count()==1: if pop_cnt%2==0: ans+=1 else: ans-=1 else: if pop_cnt%2==0: ans+=f(N-pop_cnt,UF.Group_Count()) else: ans-=f(N-pop_cnt,UF.Group_Count()) ans%=mod print(ans)