#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long ll; typedef unsigned int ui; const ll mod = 998244353; const ll INF = (ll)1000000007 * 1000000007; typedef pair P; #define stop char nyaa;cin>>nyaa; #define rep(i,n) for(int i=0;i=0;i--) #define Rep(i,sta,n) for(int i=sta;i=sta;i--) #define rep1(i,n) for(int i=1;i<=n;i++) #define per1(i,n) for(int i=n;i>=1;i--) #define Rep1(i,sta,n) for(int i=sta;i<=n;i++) typedef long double ld; const ld eps = 1e-8; const ld pi = acos(-1.0); typedef pair LP; int dx[4]={1,-1,0,0}; int dy[4]={0,0,1,-1}; template struct ModInt { long long x; ModInt() : x(0) {} ModInt(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} explicit operator int() const {return x;} ModInt &operator+=(const ModInt &p) { if((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int)(1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; } ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; } ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; } ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; } bool operator==(const ModInt &p) const { return x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const{ int a = x, b = mod, u = 1, v = 0, t; while(b > 0) { t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } return ModInt(u); } ModInt power(long long p) const{ int a = x; if (p==0) return 1; if (p==1) return ModInt(a); if (p%2==1) return (ModInt(a)*ModInt(a)).power(p/2)*ModInt(a); else return (ModInt(a)*ModInt(a)).power(p/2); } ModInt power(const ModInt p) const{ return ((ModInt)x).power(p.x); } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { long long x; is >> x; a = ModInt(x); return (is); } }; using modint = ModInt; struct ModFac{ public: vector f,i_f; int n; ModFac(int n_){ n=n_; f.resize(n+1,1); i_f.resize(n+1,1); for(int i=0;i=0;i--){ i_f[i]=i_f[i+1]*(modint)(i+1); } } ModFac(modint n_){ n=(int)n_; f.resize(n+1,1); i_f.resize(n+1,1); for(int i=0;i=0;i--){ i_f[i]=i_f[i+1]*(modint)(i+1); } } modint factorial(int x){ //cout << f.size() << endl; return f[x]; } modint inv_factorial(int x){ return i_f[x]; } modint comb(int m,int k){ if (m<0 or k<0) return 0; if (m se; vector

G[100010]; map visited; map> memo; ModFac MF(110000); void dfs(int s,int edges,int &node,int &edge,int &max_branch){ visited[s]=true; int branch=0; node+=1; for(P e:G[s]){ if(!(edges&(1 << e.second))) continue; branch+=1; edge+=1; if(visited[e.first]) continue; dfs(e.first,edges,node,edge,max_branch); } max_branch=max(max_branch,branch); } modint f(int M,int K){ if(memo[P(M,K)].second) return memo[P(M,K)].first; modint res=0; rep(i,M+1){ res+=MF.comb(M,i)*MF.factorial(i+K); } memo[P(M,K)].first=res;memo[P(M,K)].second=true; return res; } void solve(){ cin >> n >> m; rep(i,m){ int a,b;cin >> a >> b;a--;b--; se.insert(a);se.insert(b); E[i]=P(a,b); G[a].push_back(P(b,i)); G[b].push_back(P(a,i)); } int U=(1 << m); modint ans=0; rep(S,U){ modint res=0; visited.clear(); int num_cycle=0,num_pass=0,num_NG=0,others=n; //cout << bitset<15>(S) << endl; for(int a:se){ if(visited[a]) continue; int node=0,edge=0,max_branch=0; dfs(a,S,node,edge,max_branch); edge/=2; if(node==1) continue; if(node==edge+1 && max_branch<=2) num_pass+=1; if(node==edge && max_branch==2) num_cycle+=1; if(max_branch>=3) num_NG+=1; others-=node; } //cout << num_pass << " " << num_cycle << " " << num_NG << endl; //cout << others << endl; //if(num_cycle>=2) cout << bitset<15>(S) << endl; if(num_NG) continue; if(num_cycle==1 && num_pass==0) res=1; if(num_cycle==0 && num_pass>=1) { res=((modint)2).power(num_pass-1)*f(others,num_pass-1); if(n-others==2) res-=1; } //cout << res << endl; int cnt=0; rep(i,m){ if(S&(1 << i)) cnt+=1; } if(cnt%2==1) ans+=res; else ans-=res; } modint ALL=0; Rep(i,3,n+1){ ALL+=MF.factorial(n)/((modint)(2*i)*MF.factorial(n-i)); } //cout << ALL << endl; cout << ALL-ans << endl; } int main(){ ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(50); solve(); }