#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 1000005 #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace __gnu_pbds; using oset = tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update>; int root, n, L[N], R[N], A[N], alloc; oset *a[N]; i64 t[N], sz[N]; int read() { int u = ++alloc, p; cin >> p; if (p) return sz[u] = 1, A[u] = p, u; L[u] = read(); R[u] = read(); return sz[u] = sz[L[u]] + sz[R[u]], 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 dfs0(int u) { if (!L[u]) return void((a[u] = new oset())->insert({A[u], u})); dfs0(L[u]), dfs0(R[u]); i64 l2r = 0, r2l = 0; if (a[R[u]]->size() > a[L[u]]->size()) { for (const pair<int, int> &x : *a[L[u]]) l2r += a[R[u]]->order_of_key(*a[R[u]]->lower_bound({x.first, 0})), r2l += sz[R[u]] - a[R[u]]->order_of_key(*a[R[u]]->lower_bound({x.first+1, 0})); } else { for (const pair<int, int> &x : *a[R[u]]) l2r += sz[L[u]] - a[L[u]]->order_of_key(*a[L[u]]->lower_bound({x.first+1, 0})), r2l += a[L[u]]->order_of_key(*a[L[u]]->lower_bound({x.first, 0})); } if (sz[R[u]] > sz[L[u]]) { a[u] = a[R[u]]; for (auto x : *a[L[u]]) a[u]->insert(x); delete a[L[u]]; } else { a[u] = a[L[u]]; for (auto x : *a[R[u]]) a[u]->insert(x); delete a[R[u]]; } r2l=l2r=0; for (auto x : *a[L[u]]) upd(x.first, 1); for (auto x : *a[R[u]]) l2r += qry(x.first + 1); for (auto x : *a[L[u]]) upd(x.first, -1); for (auto x : *a[R[u]]) upd(x.first, 1); for (auto x : *a[L[u]]) r2l += qry(x.first + 1); for (auto x : *a[R[u]]) upd(x.first, -1); if (r2l < l2r) swap(L[u], R[u]); } vector<int> corona; void dfs2(int u) { if (!L[u]) corona.push_back(A[u]); else dfs2(L[u]), dfs2(R[u]); } int main() { ShinLena; cin >> n; root = read(); dfs0(root); dfs2(root); u64 z{0}; for (auto x : corona) upd(x, 1), z += qry(x+1); cout << z; return 0; }