#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; //#define int long long typedef long long ll; typedef unsigned long long ul; typedef unsigned int ui; constexpr ll mod = 998244353; const ll INF = mod * mod; typedef pairP; #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=1;i--) #define Rep1(i,sta,n) for(int i=sta;i<=n;i++) #define all(v) (v).begin(),(v).end() typedef pair LP; typedef long double ld; typedef pair LDP; const ld eps = 1e-12; const ld pi = acos(-1.0); ll mod_pow(ll x, ll n,ll m) { ll res = 1; while (n) { if (n & 1)res = res * x % m; x = x * x % m; n >>= 1; } return res; } struct modint { ll n; modint() :n(0) { ; } modint(ll m) :n(m) { if (n >= mod)n %= mod; else if (n < 0)n = (n % mod + mod) % mod; } operator int() { return n; } }; bool operator==(modint a, modint b) { return a.n == b.n; } modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; } modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; } modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; } modint operator+(modint a, modint b) { return a += b; } modint operator-(modint a, modint b) { return a -= b; } modint operator*(modint a, modint b) { return a *= b; } modint operator^(modint a, int n) { if (n == 0)return modint(1); modint res = (a * a) ^ (n / 2); if (n % 2)res = res * a; return res; } ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); } modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); } const int max_n = 1 << 18; modint fact[max_n], factinv[max_n]; void init_f() { fact[0] = modint(1); for (int i = 0; i < max_n - 1; i++) { fact[i + 1] = fact[i] * modint(i + 1); } factinv[max_n - 1] = modint(1) / fact[max_n - 1]; for (int i = max_n - 2; i >= 0; i--) { factinv[i] = factinv[i + 1] * modint(i + 1); } } modint comb(int a, int b) { if (a < 0 || b < 0 || a < b)return 0; return fact[a] * factinv[b] * factinv[a - b]; } struct uf { private: vector par, ran; public: uf(int n) { par.resize(n, 0); ran.resize(n, 0); rep(i, n) { par[i] = i; } } int find(int x) { if (par[x] == x)return x; else return par[x] = find(par[x]); } void unite(int x, int y) { x = find(x), y = find(y); if (x == y)return; if (ran[x] < ran[y]) { par[x] = y; } else { par[y] = x; if (ran[x] == ran[y])ran[x]++; } } bool same(int x, int y) { return find(x) == find(y); } }; map calced; map memo; modint f(int cmp, int rest) { if (calced[{cmp, rest}])return memo[{cmp, rest}]; calced[{cmp, rest}] = true; modint res = 0; rep(i, rest + 1) { res += comb(rest, i) * fact[i + cmp - 1] / fact[cmp - 1]; } return memo[{cmp, rest}] = res; } void solve(){ int n, m; cin >> n >> m; vector a(m), b(m); rep(i, m) { cin >> a[i] >> b[i]; a[i]--; b[i]--; } modint ans = 0; for (int c = 3; c <= n; c++) { ans += comb(n, c) * fact[c - 1] * (modint)((1 + mod) / 2); } rep1(i, (1 << m) - 1) { vector

vs; vector vx; rep(j, m)if (i & (1 << j)) { vs.push_back({ a[j],b[j] }); vx.push_back(a[j]); vx.push_back(b[j]); } sort(all(vx)); vx.erase(unique(all(vx)), vx.end()); rep(j, vs.size()) { vs[j].first = lower_bound(all(vx), vs[j].first) - vx.begin(); vs[j].second = lower_bound(all(vx), vs[j].second) - vx.begin(); } vector cnt(vx.size()); rep(j, vs.size()) { cnt[vs[j].first]++; cnt[vs[j].second]++; } bool exi3 = false; rep(j, vx.size()) { if (cnt[j] >= 3)exi3 = true; } if (exi3)continue; uf u(vx.size()+1); bool isc = false; rep(j, vs.size()) { int l = vs[j].first, r = vs[j].second; if (u.same(l, r))isc = true; else u.unite(l, r); } int cmp = 0; rep(j, vx.size()) { if (!u.same(j, vx.size())) { cmp++; u.unite(j, vx.size()); } } if (isc) { if (cmp == 1) { if (vs.size() % 2)ans -= 1; else ans += 1; } continue; } int rest = n - vx.size(); modint csum = f(cmp, rest); if (vs.size() == 1)csum -= 1; else { rep(tt, cmp - 1)csum *= 2; csum *= fact[cmp - 1]; } //cout << i << " ? " << csum << " "<> t; rep(i, t) solve(); return 0; }