#include #include #include #include #include #include #include using namespace std; using ll = long long; ll r; struct Graph { struct Vertex { int n, k; }; struct Edge { int i, n; }; Graph(int n, int m) : v(n, { -1, 0 }), e(m), n(n), m(0) {} void add_edge(int a, int b) { e[m] = { b, v[a].n }; v[a].n = m; m++; } int dfs(int i, int p) { ll k = 0; for (int j = v[i].n; j >= 0; j = e[j].n) { Edge &o = e[j]; if (o.i == p) continue; k += dfs(o.i, i); } r += (n - (k + 1)) * (k + 1); r += n; for (int j = v[i].n; j >= 0; j = e[j].n) { Edge &o = e[j]; if (o.i == p) continue; r += (ll)v[o.i].k * (n - v[o.i].k); } return v[i].k = k + 1; } vector v; vector e; int n, m; }; int main() { ios::sync_with_stdio(false); cin.tie(0); int n; cin >> n; Graph g(n, (n - 1) * 2); for (int i = 0; i < n - 1; i++) { int a, b; cin >> a >> b; a--; b--; g.add_edge(a, b); g.add_edge(b, a); } r = 0; g.dfs(0, -1); cout << r << endl; return 0; }