#pragma region Macros #pragma GCC optimize("O3") #include #define ll long long #define ld long double #define rep2(i, a, b) for(ll i = a; i <= b; ++i) #define rep(i, n) for(ll i = 0; i < n; ++i) #define rep3(i, a, b) for(ll i = a; i >= b; --i) #define pii pair #define pll pair #define pb push_back #define eb emplace_back #define vi vector #define vll vector #define vpi vector #define vpll vector #define overload2(_1, _2, name, ...) name #define vec(type, name, ...) vector name(__VA_ARGS__) #define VEC(type, name, size) \ vector name(size); \ IN(name) #define vv(type, name, h, ...) vector> name(h, vector(__VA_ARGS__)) #define VV(type, name, h, w) \ vector> name(h, vector(w)); \ IN(name) #define vvv(type, name, h, w, ...) vector>> name(h, vector>(w, vector(__VA_ARGS__))) #define fi first #define se second #define all(c) begin(c), end(c) #define ios ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0); #define lb(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define ub(c, x) distance((c).begin(), upper_bound(all(c), (x))) using namespace std; template using pq = priority_queue; template using pqg = priority_queue, greater>; #define Size(c) (int)(c).size() #define INT(...) \ int __VA_ARGS__; \ IN(__VA_ARGS__) #define LL(...) \ ll __VA_ARGS__; \ IN(__VA_ARGS__) #define ULL(...) \ ull __VA_ARGS__; \ IN(__VA_ARGS__) #define STR(...) \ string __VA_ARGS__; \ IN(__VA_ARGS__) #define CHR(...) \ char __VA_ARGS__; \ IN(__VA_ARGS__) #define DBL(...) \ double __VA_ARGS__; \ IN(__VA_ARGS__) #define LD(...) \ ld __VA_ARGS__; \ IN(__VA_ARGS__) int scan() { return getchar(); } template void scan(T a) { cin >> a; } void scan(int &a) { cin >> a; } void scan(long long &a) { cin >> a; } void scan(char &a) { cin >> a; } void scan(double &a) { cin >> a; } void scan(long double &a) { cin >> a; } void scan(char a[]) { scanf("%s", a); } void scan(string &a) { cin >> a; } template void scan(vector &); template void scan(array &); template void scan(pair &); template void scan(T (&)[size]); template void scan(vector &a) { for(auto &i : a) scan(i); } template void scan(deque &a) { for(auto &i : a) scan(i); } template void scan(array &a) { for(auto &i : a) scan(i); } template void scan(pair &p) { scan(p.first); scan(p.second); } template void scan(T (&a)[size]) { for(auto &i : a) scan(i); } template void scan(T &a) { cin >> a; } void IN() {} template void IN(Head &head, Tail &... tail) { scan(head); IN(tail...); } string stin() { string s; cin >> s; return s; } template inline bool chmax(T &a, S b) { if(a < b) { a = b; return 1; } return 0; } template inline bool chmin(T &a, S b) { if(a > b) { a = b; return 1; } return 0; } vi iota(int n) { vi a(n); iota(all(a), 0); return a; } template void UNIQUE(vector &x) { sort(all(x)); x.erase(unique(all(x)), x.end()); } int in() { int x; cin >> x; return x; } ll lin() { unsigned long long x; cin >> x; return x; } void print() { putchar(' '); } void print(bool a) { cout << a; } void print(int a) { cout << a; } void print(long long a) { cout << a; } void print(char a) { cout << a; } void print(string &a) { cout << a; } void print(double a) { cout << a; } template void print(const vector &); template void print(const array &); template void print(const pair &p); template void print(const T (&)[size]); template void print(const vector &a) { if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end();) { cout << " "; print(*i); } cout << endl; } template void print(const deque &a) { if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end();) { cout << " "; print(*i); } } template void print(const array &a) { print(a[0]); for(auto i = a.begin(); ++i != a.end();) { cout << " "; print(*i); } } template void print(const pair &p) { cout << '('; print(p.first); cout << ","; print(p.second); cout << ')'; } template void print(set &x) { for(auto e : x) print(e), cout << " "; cout << endl; } template void print(multiset &x) { for(auto e : x) print(e), cout << " "; cout << endl; } template void print(const T (&a)[size]) { print(a[0]); for(auto i = a; ++i != end(a);) { cout << " "; print(*i); } } template void print(const T &a) { cout << a; } int out() { putchar('\n'); return 0; } template int out(const T &t) { print(t); putchar('\n'); return 0; } template int out(const Head &head, const Tail &... tail) { print(head); putchar(' '); out(tail...); return 0; } ll gcd(ll a, ll b) { while(b) { ll c = b; b = a % b; a = c; } return a; } ll lcm(ll a, ll b) { if(!a || !b) return 0; return a * b / gcd(a, b); } vector factor(ll x) { vector ans; for(ll i = 2; i * i <= x; i++) if(x % i == 0) { ans.push_back({i, 1}); while((x /= i) % i == 0) ans.back().second++; } if(x != 1) ans.push_back({x, 1}); return ans; } vector divisor(int x) { vector ans; for(int i = 1; i * i <= x; i++) if(x % i == 0) { ans.pb(i); if(i * i != x) ans.pb(x / i); } return ans; } template void zip(vector &x) { vector y = x; sort(all(y)); for(int i = 0; i < x.size(); ++i) { x[i] = lb(y, x[i]); } } int popcount(ll x) { return __builtin_popcountll(x); } mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); int rnd(int n) { return uniform_int_distribution(0, n - 1)(rng); } template void shuffle(vector &v) { rep3(i, v.size() - 1, 1) { swap(v[i], v[rnd(i)]); } } #define endl '\n' vector YES{"NO", "YES"}; vector Yes{"No", "Yes"}; vector yes{"no", "yes"}; #ifdef _LOCAL #undef endl #define debug(x) \ cout << #x << ": "; \ print(x); \ cout << endl; void err() {} template void err(const T &t) { print(t); cout << " "; } template void err(const Head &head, const Tail &... tail) { print(head); putchar(' '); out(tail...); } #else #define debug(x) template void err(const T &...) {} #endif template struct edge { int from, to; T cost; int id; edge(int to, T cost) : from(-1), to(to), cost(cost) {} edge(int from, int to, T cost) : from(from), to(to), cost(cost) {} // edge(int from,int to,T cost,int id):from(from),to(to),cost(cost),id(id){} edge &operator=(const int &x) { to = x; return *this; } operator int() const { return to; } }; template using Edges = vector>; struct Graph : vector> { using vector>::vector; inline void add(int a, int b, bool directed = false) { (*this)[a].emplace_back(b); if(!directed) (*this)[b].emplace_back(a); } void read(int n = -1, int offset = 1) { if(n == -1) n = this->size() - 1; int a, b; while(n--) { cin >> a >> b; Graph::add(a - offset, b - offset); } } }; template struct WeightedGraph : vector> { using vector>::vector; inline void add(int a, int b, T c, bool directed = false) { (*this)[a].emplace_back(b, c); if(!directed) (*this)[b].emplace_back(a, c); } void read(int n = -1, int offset = 1) { if(n == -1) n = this->size() - 1; int a, b; while(n--) { cin >> a >> b; Graph::add(a - offset, b - offset); } } }; struct Setup_io { Setup_io() { ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0); cout << fixed << setprecision(15); } } setup_io; #pragma endregion // _________コーディングはここから!!___________ namespace modular { constexpr ll MOD = 998244353; const int MAXN = 1100000; template class modint { using u64 = ll; public: u64 a; constexpr modint(const u64 x = 0) noexcept : a(((x % Modulus) + Modulus) % Modulus) {} constexpr u64 &value() noexcept { return a; } constexpr const u64 &value() const noexcept { return a; } constexpr modint operator+(const modint rhs) const noexcept { return modint(*this) += rhs; } constexpr modint operator-(const modint rhs) const noexcept { return modint(*this) -= rhs; } constexpr modint operator*(const modint rhs) const noexcept { return modint(*this) *= rhs; } template constexpr modint operator^(T rhs) const noexcept { return modint(*this) ^= rhs; } constexpr modint &operator+=(const modint rhs) noexcept { a += rhs.a; if(a >= Modulus) { a -= Modulus; } return *this; } constexpr modint &operator-=(const modint rhs) noexcept { if(a < rhs.a) { a += Modulus; } a -= rhs.a; return *this; } constexpr modint &operator*=(const modint rhs) noexcept { a = a * rhs.a % Modulus; return *this; } constexpr bool operator==(const modint rhs) const noexcept { return a == rhs.a; } template constexpr modint &operator^=(T n) noexcept { modint res = 1; modint x = a; while(n) { if(n & 1) res *= x; x *= x; n >>= 1; } a = res.a; return *this; } }; #define mint modint #define vmint vector vmint Inv{0, 1}, Prd{1, 1}, Invprd{1, 1}; mint inv(int n) { if(Inv.size() > n) return Inv[n]; else { for(int i = Inv.size(); i <= n; ++i) Inv.emplace_back(Inv[MOD % i] * (-MOD / i)); return Inv[n]; } } mint prd(int n) { if(Prd.size() > n) return Prd[n]; else for(int i = Prd.size(); i <= n; ++i) Prd.emplace_back(Prd[i - 1] * i); return Prd[n]; } mint invprd(int n) { if(Invprd.size() > n) return Invprd[n]; else for(int i = Invprd.size(); i <= n; ++i) Invprd.emplace_back(Invprd[i - 1] * inv(i)); return Invprd[n]; } mint modpow(ll a, ll n) { mint x = a; return x ^= n; } template modint operator/(modint l, modint r) { if(r.a < MAXN) return l * inv(r.a); return l * (r ^ (MOD - 2)); } template modint operator/(T l, modint r) { return modint(l) / r; } template modint operator/=(modint &l, modint r) { return l = l / r; } mint C(int a, int b) { if(a < 0 || b < 0) return 0; if(a < b) return 0; return prd(a) * invprd(b) * invprd(a - b); } mint P(int a, int b) { if(a < 0 || b < 0) return 0; if(a < b) return 0; return prd(a) * invprd(a - b); } ostream &operator<<(ostream &os, mint a) { os << a.a; return os; } template ostream &operator<<(ostream &os, vector &a) { for(auto &e : a) os << e << " "; os << endl; return os; } istream &operator>>(istream &is, mint &a) { ll x; is >> x; a = x; return is; } } // namespace modular using namespace modular; template struct UnionFind { vector data; vector sz; bool is_default; UnionFind(int n) { data.assign(n, -1); sz.assign(n, 1); is_default = true; } UnionFind(int n, vector &a) { data.assign(n, -1); sz = a; is_default = false; } bool unite(int x, int y) { x = find(x), y = find(y); if(x == y) return false; if(data[x] > data[y]) swap(x, y); data[x] += data[y]; if(!is_default) sz[x] += sz[y]; data[y] = x; return true; } bool same(int x, int y) { return find(x) == find(y); } int find(int x) { if(data[x] < 0) return x; return (data[x] = find(data[x])); } T size(int x) { return (is_default ? -data[find(x)] : sz[find(x)]); } }; main() { INT(n, m); vector v; rep(i, m) { INT(a, b); v.eb(a - 1, b - 1); } mint ans; rep2(i, 3, n) { ans += P(n, i) / (mint)i; } map mem; rep(mask, 1 << m) { int t = popcount(mask) & 1; int a = 0, b = 0; int e = popcount(mask); mint s = (e & 1 ? -1 : 1); bool flag = true; // a : 連結成分の数 // b : 頂点数 // e : 辺数 UnionFind uf(n); map mp; int cnt = 0; rep(i, m) { if(mask & 1 << i) { auto [x, y] = v[i]; if(!mp.count(x)) mp[x] = cnt++; if(!mp.count(y)) mp[y] = cnt++; uf.unite(mp[x], mp[y]); } } b = cnt; rep(i, cnt) if(uf.find(i) == i) a++; vi g(cnt); rep(i, m) if(mask & 1 << i) g[mp[v[i].fi]]++, g[mp[v[i].se]]++; rep(i, cnt) if(g[i] > 2) flag = false; if(!flag) continue; if(b - e == a) { if(mem.count(pii(a, b))) ans += s * mem[{a, b}] * modpow(2, a) * P(a, a) / (mint)a; else { mint res; rep(j, n - b + 1) { if(j + b > 2) res += P(n - b, j) * C(j + a - 1, a - 1); } mem[pii(a, b)] = res; ans += s * res * modpow(2, a) * P(a, a) / (mint)a; } } else if(a == 1) { ans += s * 2; } } cout << ans / (mint)2 << endl; }