#include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x ostream& operator<<(ostream& os, const pair& p){ return os << "{" << p.first << ", " << p.second << "}"; } template ostream& operator<<(ostream& os, const vector& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; } template ostream& operator<<(ostream& os, const set& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; } template ostream& operator<<(ostream& os, const map& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; } #ifdef ONLINE_JUDGE #define dump(expr) ; #else #define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; } #endif using EdgeCost = ll; struct E { int fr, to, eid; EdgeCost cost; E(int fr_, int to_, int eid_, EdgeCost cost_) : fr(fr_), to(to_), eid(eid_), cost(cost_) {} friend ostream &operator<<(ostream &os, const E &e) { os << "(" << e.fr << " -> " << e.to << ")"; return os; } }; using V = vector; struct G { int n, e_count; vector adj; vector rev; G(int n_ = 0) : n(n_), e_count(0), adj(n), rev(n) {} void add_directed_edge(int fr, int to, EdgeCost cost = (EdgeCost)1) { int eid = e_count; adj[fr].push_back(E(fr, to, eid, cost)); rev[to].push_back(E(fr, to, eid, cost)); e_count++; } void add_undirected_edge(int fr, int to, EdgeCost cost = (EdgeCost)1) { int eid = e_count; adj[fr].push_back(E(fr, to, eid, cost)); rev[to].push_back(E(fr, to, eid, cost)); adj[to].push_back(E(to, fr, eid, cost)); rev[fr].push_back(E(to, fr, eid, cost)); e_count++; } }; struct StronglyConnectedComponents { vector visited; vector t_order; vector comp; int n_comps; StronglyConnectedComponents() {} // normal topological sort void dfs1(G &g, int id, int &k) { visited[id] = true; for (auto it : g.adj[id]) if (!visited[it.to]) dfs1(g, it.to, k); t_order[--k] = id; } // dfs of reverse order void dfs2(G &g, int id, int &k) { visited[id] = true; for (auto it : g.rev[id]) if (!visited[it.fr]) dfs2(g, it.fr, k); comp[id] = k; // foreach vertex "id", return the topological order } void exec(G &g) { int k = g.n; // 1st dfs visited.assign(g.n, 0); t_order.assign(g.n, 0); comp.assign(g.n, 0); for (int j : range(g.n)) if (!visited[j]) dfs1(g, j, k); // 2nd dfs visited.assign(g.n, 0); for (int i : range(g.n)) { int j = t_order[i]; if (!visited[j]) dfs2(g, j, k), k++; } n_comps = k; } }; namespace solver { int n; G g; void read() { cin >> n; g = G(n + 1); for (int i : range(n)) { int k; cin >> k; for ([[maybe_unused]]int j : range(k)) { int a; cin >> a; g.add_directed_edge(i + 1, a); } } } G gsh; vector sz; vector memo; int dfs(int idx) { if (memo[idx] >= 0) return memo[idx]; int res = 0; for (auto e : gsh.adj[idx]) { res = max(res, dfs(e.to)); } res += sz[idx]; return memo[idx] = res; } ll run() { dump(g.adj); StronglyConnectedComponents scc; scc.exec(g); gsh = G(scc.n_comps); sz.assign(scc.n_comps, 0); for (int i : range(n + 1)) { for (auto e : g.adj[i]) { int fr = scc.comp[e.fr]; int to = scc.comp[e.to]; assert(fr <= to); dump(fr << " " << to) if (fr != to) gsh.add_directed_edge(fr, to); } sz[scc.comp[i]]++; } dump(sz) dump(gsh.adj) memo.assign(scc.n_comps, -1); for (int i : range(scc.n_comps)) if (dfs(i) == n) return 1; return 0; } } // namespace int main(int argc, char** argv) { cerr << fixed << setprecision(12); cout << fixed << setprecision(12); int testcase = 1; if (argc > 1) testcase = atoi(argv[1]); while (testcase--) { solver::read(); } cout << (solver::run() ? "Yes" : "No") << endl; }