#include namespace { #pragma GCC diagnostic ignored "-Wunused-function" #include #pragma GCC diagnostic warning "-Wunused-function" using namespace std; using namespace atcoder; #define rep(i,n) for(int i = 0; i < (int)(n); i++) #define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--) #define all(x) begin(x), end(x) #define rall(x) rbegin(x), rend(x) template bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; } template bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; } using ll = long long; using P = pair; using VI = vector; using VVI = vector; using VL = vector; using VVL = vector; } int main() { ios::sync_with_stdio(false); cin.tie(0); int n; cin >> n; VVI to(n); rep(i, n - 1) { int u, v; cin >> u >> v; u--, v--; to[u].emplace_back(v); to[v].emplace_back(u); } using A = array; ll ans = 0; auto dfs = [&](auto&& self, int u, int p) -> A { A now{1, 0, 0}; for (int v : to[u]) if (v != p) { auto res = self(self, v, u); auto acc = res; rep(i, 2) acc[i+1] += acc[i]; rep(i, 3) ans += (ll)acc[i] * now[2 - i]; rep(i, 2) now[i+1] += res[i]; } return now; }; dfs(dfs, 0, -1); cout << ans << '\n'; }