#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define llint long long #define inf 1e18 #define rep(x, s, t) for(llint (x) = (s); (x) < (t); (x)++) #define Rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++) #define chmin(x, y) (x) = min((x), (y)) #define chmax(x, y) (x) = max((x), (y)) #define mod 998244353 using namespace std; typedef pair P; struct UnionFind{ int size; vector parent; UnionFind(){} UnionFind(int size){ this->size = size; parent.resize(size+1); init(); } void init(){ for(int i = 0; i <= size; i++) parent[i] = i; } int root(int i){ if(parent[i] == i) return i; return parent[i] = root(parent[i]); } bool same(int i, int j){ return root(i) == root(j); } void unite(int i, int j){ int root_i = root(i), root_j = root(j); if(root_i == root_j) return; parent[root_i] = root_j; } }; const int FACT_MAX = 200005; llint fact[FACT_MAX], fact_inv[FACT_MAX]; llint modpow(llint a, llint n) { if(n == 0) return 1; if(n % 2){ return ((a%mod) * (modpow(a, n-1)%mod)) % mod; } else{ return modpow((a*a)%mod, n/2) % mod; } } void make_fact() { llint val = 1; fact[0] = 1; for(int i = 1; i < FACT_MAX; i++){ val *= i; val %= mod; fact[i] = val; } fact_inv[FACT_MAX-1] = modpow(fact[FACT_MAX-1], mod-2); for(int i = FACT_MAX-2; i >= 0; i--){ fact_inv[i] = fact_inv[i+1] * (i+1) % mod; } } llint comb(llint n, llint k) { llint ret = 1; ret *= fact[n]; ret *= fact_inv[k], ret %= mod; ret *= fact_inv[n-k], ret %= mod; return ret; } llint n, m; llint a[20], b[20]; llint num[20][40]; vector G[100005], vec; UnionFind uf(100005); llint pop[1<<16]; llint beki[40]; int main(void) { ios::sync_with_stdio(0); cin.tie(0); make_fact(); cin >> n >> m; for(int i = 0; i < m; i++){ cin >> a[i] >> b[i]; a[i]--, b[i]--; vec.push_back(a[i]); vec.push_back(b[i]); } sort(vec.begin(), vec.end()); vec.erase(unique(vec.begin(), vec.end()), vec.end()); beki[0] = 1; for(int i = 1; i < 40; i++) beki[i] = beki[i-1] * 2 % mod; for(int i = 0; i <= m; i++){ for(int j = 0; j <= 2*m; j++){ for(int k = max(0, 3-j); k <= n-j; k++){ num[i][j] += comb(n-j, k) * fact[k+i-1] % mod; num[i][j] %= mod; } num[i][j] *= ((mod+1)/2), num[i][j] %= mod; num[i][j] *= beki[i], num[i][j] %= mod; } } llint M = 1< S; for(int j = 0; j < m; j++){ if(i & (1<= 3) flag = false; } if(cycle >= 2) continue; if(cycle){ for(int j = 0; j < vec.size(); j++){ if(G[vec[j]].size() == 1) flag = false; } } if(!flag) continue; map mp; for(int j = 0; j < vec.size(); j++) mp[uf.root(vec[j])]++; llint c = 0, x = S.size(); for(auto it = mp.begin(); it != mp.end(); it++){ if(it->second >= 2) c++; } llint tmp = num[c][x]; if(cycle) tmp = 1; if(pop[i] % 2 == 0) ans += tmp, ans %= mod; else ans += mod - tmp, ans %= mod; //cout << i << " " << c << " " << x << " " << tmp << " " << cycle << endl; } cout << ans << endl; return 0; }