func_code_string: #include <bits/stdc++.h>   #pragma GCC optimize( O3 )   const double PI = acos(-1);   template <class A, class B>   std::ostream& operator<<(std::ostream& st, const std::pair<A, B> p) {     st <<  (  << p.first <<  ,   << p.second <<  ) ;     return st;   }   using namespace std;   const int MAX = 100 * 1000 + 10;   mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());   std::vector<int> cand_base{26,  29,  31,  37,  41,  43,  47,  53, 59,                              61,  67,  71,  73,  79,  83,  89,  97, 101,                              103, 107, 109, 113, 127, 131, 137, 139};   std::vector<int> cand_mod{1000001273, 1000001279, 1000001311, 1000001329,                             1000001333};   int base[2], mod[2], base_power[2][MAX];   int n;   std::vector<int> adj[MAX];   int siz[MAX];   int add(int a, int b, int m) {     a += b;     if (a >= m) a -= m;     if (a < 0) a += m;     if (a >= m || a < 0) a = (a % m + m) % m;     return a;   }   int mul(int a, int b, int m) { return (a * (long long)b) % m; }   void init_hashing() {     srand(0);     shuffle(cand_base.begin(), cand_base.end(), rng);     shuffle(cand_mod.begin(), cand_mod.end(), rng);     for (int i = 0; i < (2); i++) base[i] = cand_base[i] + n;     for (int i = 0; i < (2); i++) mod[i] = cand_mod[i];     for (int i = 0; i < (2); i++) base_power[i][0] = 1;     for (int i = 0; i < 2; i++)       for (int j = 0; j < MAX - 1; j++)         base_power[i][j + 1] = mul(base_power[i][j], base[i], mod[i]);   }   struct DS {     map<std::pair<int, int>, int> cnt;     void add(std::pair<int, int> x, int v) {       cnt[x] += v;       if (cnt[x] == 0)         cnt.erase(x);       else         assert(cnt[x] > 0);     }   };   std::pair<int, int> f[MAX];   vector<pair<std::pair<int, int>, int>> children[MAX];   DS ds;   std::pair<int, int> merge(std::pair<int, int> L, std::pair<int, int> R,                             int len) {     std::pair<int, int> h;     h.first = add(mul(L.first, base_power[0][len], mod[0]), R.first, mod[0]);     h.second = add(mul(L.second, base_power[1][len], mod[1]), R.second, mod[1]);     return h;   }   std::pair<int, int> dfs(int u, int p) {     auto& C = children[u];     for (int v : adj[u])       if (v != p) {         auto tmp = dfs(v, u);         C.emplace_back(tmp, v);         siz[u] += siz[v];       }     sort(C.begin(), C.end());     f[u] = std::pair<int, int>(0, 0);     siz[u] = 1;     for (auto [h, v] : C) {       f[u] = merge(f[u], h, siz[v]);       siz[u] += siz[v];     }     f[u] = merge(f[u], std::pair<int, int>(siz[u], siz[u]), 1);     ds.add(f[u], 1);     return f[u];   }   std::pair<int, int> ans;   void dfs(int u, int p, std::pair<int, int> fp) {     std::pair<int, int> old = f[u];     ds.add(old, -1);     ans = max(ans, std::pair<int, int>(ds.cnt.size(), -u));     auto& C = children[u];     if (p) {       C.emplace_back(fp, p);       sort(C.begin(), C.end());     }     int m = ((int)C.size());     std::vector<int> sizes(m);     std::vector<std::pair<int, int>> suff(m);     for (int i = 0; i < (m); i++) {       int v = C[i].second;       sizes[i] = (v == p) ? (n - siz[u]) : siz[v];     }     for (int i = m - 1, tot = 0; i > 0; i--) {       std::pair<int, int> h = C[i].first;       suff[i - 1] = merge(h, suff[i], tot);       tot += sizes[i];     }     std::pair<int, int> H(0, 0);     int tot = 0;     for (int i = 0; i < (m); i++) {       auto [h, v] = C[i];       int s = sizes[i];       std::pair<int, int> tmp = merge(H, suff[i], n - 1 - s - tot);       tmp = merge(tmp, std::pair<int, int>(n - s, n - s), 1);       ds.add(tmp, 1);       if (v != p) dfs(v, u, tmp);       ds.add(tmp, -1);       H = merge(H, h, s);       tot += s;     }     ds.add(old, 1);   }   int main() {     scanf( %d , &n);     for (int e = 0; e < (n - 1); e++) {       int a, b;       scanf( %d %d , &a, &b);       adj[a].push_back(b);       adj[b].push_back(a);     }     init_hashing();     dfs(1, 0);     ans = std::pair<int, int>(-1, 0);     dfs(1, 0, std::pair<int, int>(0, 0));     cout << -ans.second << endl;     return 0;   }   