#include using namespace std; using std::cerr; using std::cin; using std::cout; #if __has_include() #include using mint = atcoder::modint998244353; istream &operator>>(istream &is, mint &a) { long long t; is >> t; a = t; return is; } ostream &operator<<(ostream &os, mint a) { return os << a.val(); } #endif typedef long double ld; #define long long long #define uint unsigned int #define ull unsigned long #define overload3(a, b, c, name, ...) name #define rep3(i, a, b) for (int i = (a); i < (b); i++) #define rep2(i, n) rep3(i, 0, n) #define rep1(n) rep2(__i, n) #define rep(...) overload3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__) #define per3(i, a, b) for (int i = (b) - 1; i >= (a); i--) #define per2(i, n) per3(i, 0, n) #define per1(n) per2(__i, n) #define per(...) overload3(__VA_ARGS__, per3, per2, per1)(__VA_ARGS__) #define all(a) a.begin(), a.end() #define UNIQUE(a) \ sort(all(a)); \ a.erase(unique(all(a)), a.end()) #define sz(a) (int)a.size() #define vec vector #ifndef DEBUG #define cerr \ if (0) \ cerr // #undef assert // #define assert(...) void(0) #undef endl #define endl '\n' #endif template ostream &operator<<(ostream &os, vector a) { const int n = a.size(); rep(i, n) { os << a[i]; if (i + 1 != n) os << " "; } return os; } template ostream &operator<<(ostream &os, array a) { rep(i, n) { os << a[i]; if (i + 1 != n) os << " "; } return os; } template istream &operator>>(istream &is, vector &a) { for (T &i : a) is >> i; return is; } template bool chmin(T &x, S y) { if ((T)y < x) { x = (T)y; return true; } return false; } template bool chmax(T &x, S y) { if (x < (T)y) { x = (T)y; return true; } return false; } template void operator++(vector &a) { for (T &i : a) ++i; } template void operator--(vector &a) { for (T &i : a) --i; } template void operator++(vector &a, int) { for (T &i : a) i++; } template void operator--(vector &a, int) { for (T &i : a) i--; } /* r を根として固定 V dfs(vertex v){ E prod = e(); for ( c in child(v) ){ prod = merge(prod, put_edge(dfs(c),idx(v,c))); } return put_vertex(prod, v); } r=0,...,n-1 に対し r を根として dfs(r) の値を求める */ // add_edge -> build -> reroot に答え template struct RerootingDP { struct edge { int to, idx, xdi; }; RerootingDP(int n_ = 0) : n(n_), inner_edge_id(0) { es.resize(2 * n - 2); start.resize(2 * n - 2); if (n == 1) es_build(); } void add_edge(int u, int v, int idx, int xdi) { start[inner_edge_id] = u; es[inner_edge_id] = {v, idx, xdi}; inner_edge_id++; start[inner_edge_id] = v; es[inner_edge_id] = {u, xdi, idx}; inner_edge_id++; if (inner_edge_id == 2 * n - 2) { es_build(); } } vector build(int root_ = 0) { root = root_; vector subdp(n); subdp[0] = put_vertex(e(), 0); outs.resize(n); vector geta(n + 1, 0); for (int i = 0; i < n; i++) geta[i + 1] = start[i + 1] - start[i] - 1; geta[root + 1]++; for (int i = 0; i < n; i++) geta[i + 1] += geta[i]; auto dfs = [&](auto sfs, int v, int f) -> void { E val = e(); for (int i = start[v]; i < start[v + 1]; i++) { if (es[i].to == f) { swap(es[start[v + 1] - 1], es[i]); } if (es[i].to == f) continue; sfs(sfs, es[i].to, v); E nval = put_edge(subdp[es[i].to], es[i].idx); outs[geta[v]++] = nval; val = merge(val, nval); } subdp[v] = put_vertex(val, v); }; dfs(dfs, root, -1); return subdp; } vector reroot() { vector reverse_edge(n); reverse_edge[root] = e(); vector answers(n); auto dfs = [&](auto sfs, int v) -> void { int le = outs_start(v); int ri = outs_start(v + 1); int siz = ri - le; vector rui(siz + 1); rui[siz] = e(); for (int i = siz - 1; i >= 0; i--) { rui[i] = merge(outs[le + i], rui[i + 1]); } answers[v] = put_vertex(merge(rui[0], reverse_edge[v]), v); E lui = e(); for (int i = 0; i < siz; i++) { V rdp = put_vertex( merge(merge(lui, rui[i + 1]), reverse_edge[v]), v); reverse_edge[es[start[v] + i].to] = put_edge(rdp, es[start[v] + i].xdi); lui = merge(lui, outs[le + i]); sfs(sfs, es[start[v] + i].to); } }; dfs(dfs, root); return answers; } private: int n, root, inner_edge_id; vector outs; vector es; vector start; int outs_start(int v) { int res = start[v] - v; if (root < v) res++; return res; } void es_build() { vector nes(2 * n - 2); vector nstart(n + 2, 0); for (int i = 0; i < 2 * n - 2; i++) nstart[start[i] + 2]++; for (int i = 0; i < n; i++) nstart[i + 1] += nstart[i]; for (int i = 0; i < 2 * n - 2; i++) nes[nstart[start[i] + 1]++] = es[i]; swap(es, nes); swap(start, nstart); } }; using vi = vec; vi merge(vi a, vi b) { for (auto i : b) a.push_back(i); return a; } vi e() { return {0}; } vi put_edge(vi a, int) { return {1 + *max_element(all(a))}; } vi put_vertex(vi a, int) { return a; } void solve() { int n; cin >> n; RerootingDP g(n); rep(i, n - 1) { int u, v; cin >> u >> v; u--, v--; g.add_edge(u, v, -1, -1); } g.build(); auto res = g.reroot(); long ans = 0; for (vi &a : res) { sort(all(a), greater()); rep(i, sz(a)) { chmax(ans, (i + 1) * a[i]); } } cout << ans + 1 << endl; } int main() { // srand((unsigned)time(NULL)); cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); int t = 1; // cin >> t; while (t--) solve(); }