#include <iostream> #include <cstring> #include <vector> #include <algorithm> #include <deque> #include <set> #include <utility> #include <array> using i64 = long long; using u64 = unsigned long long; using f64 = double; using f80 = long double; using namespace std; #define ALL(x) x.begin(), x.end() #define ShinLena cin.tie(nullptr)->sync_with_stdio(false); #define N 200005 int root, n, L[N], R[N], A[N], alloc; vector<int> *a[N]; i64 t[N]; int read() { int u = ++alloc, p; cin >> p; if (p) return A[u] = p, u; L[u] = read(); R[u] = read(); return u; } static inline i64 qry(u64 p) { u64 z{0}; for (; p < N; p+=p&-p) z += t[p]; return z; } static inline void upd(u64 p, i64 k) { for (; p; p-=p&-p) t[p] += k; } void dfs(int u) { if (!L[u]) return void(a[u] = new vector<int>({A[u]})); dfs(L[u]), dfs(R[u]); u64 l2r = 0, r2l = 0; for (auto x : *a[L[u]]) upd(x, 1); for (auto x : *a[R[u]]) l2r += qry(x + 1); for (auto x : *a[L[u]]) upd(x, -1); for (auto x : *a[R[u]]) upd(x, 1); for (auto x : *a[L[u]]) r2l += qry(x + 1); for (auto x : *a[R[u]]) upd(x, -1); if (l2r > r2l) swap(L[u], R[u]); if (a[R[u]]->size() > a[L[u]]->size()) { a[u] = a[R[u]]; for (auto x : *a[L[u]]) a[u]->push_back(x); delete a[L[u]]; } else { a[u] = a[L[u]]; for (auto x : *a[R[u]]) a[u]->push_back(x); delete a[R[u]]; } } vector<int> corona; void dfs1(int u) { if (!L[u]) corona.push_back(A[u]); else dfs1(L[u]), dfs1(R[u]); } int main() { ShinLena; cin >> n; root = read(); dfs(root); dfs1(root); u64 z{0}; for (auto x : corona) upd(x, 1), z += qry(x+1); cout << z; return 0; }