#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define ov4(a, b, c, d, name, ...) name
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for (ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for (auto &&e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S> bool chmin(T &a, const S &b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T, typename S> bool chmax(T &a, const S &b) {
  return a < b ? a = b, 1 : 0;
}
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
#define i128 __int128_t
struct _ {
  _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

int main() {
  int N;
  cin >> N;
  vl W(N);
  fore(i, W) cin >> i;
  ll sumW = accumulate(all(W), 0ll);
  vector G(N, vi());
  rep(N - 1) {
    int A, B;
    cin >> A >> B;
    --A, --B;
    G[A].push_back(B);
    G[B].push_back(A);
  }

  vl subt = W;

  auto dfs = [&](auto f, int v, int p) -> ll {
    for (int u : G[v]) {
      if (u != p)
        subt[v] += f(f, u, v);
    }
    return subt[v];
  };

  dfs(dfs, 0, -1);

  vector<set<ll>> wmemo(N);
  vector<set<ll> *> wset(N);
  rep(i, N) { wset[i] = &wmemo[i]; }

  ll ans = sumW;
  auto calc_ans = [&](auto f, int v, int p) -> void {
    for (int u : G[v]) {
      if (u != p)
        f(f, u, v);
    }
    for (int u : G[v]) {
      if (u != p) {
        if (sz(*wset[v]) < sz(*wset[u])) {
          swap(wset[v], wset[u]);
        }
        for (ll s1 : *wset[u]) {
          auto it = (*wset[v]).lower_bound((sumW - s1 + 1) / 2);
          if (it != (*wset[v]).end()) {
            chmin(ans, max({s1, (*it), sumW - s1 - (*it)}) -
                           min({s1, (*it), sumW - s1 - (*it)}));
          }
          if (it != (*wset[v]).begin()) {
            --it;
            chmin(ans, max({s1, (*it), sumW - s1 - (*it)}) -
                           min({s1, (*it), sumW - s1 - (*it)}));
          }
        }
        for (ll s1 : *wset[u]) {
          wset[v]->insert(s1);
        }
      }
    }
    if (p != -1) {
      auto it = (*wset[v]).lower_bound((subt[v] + 1) / 2);
      if (it != (*wset[v]).end()) {
        chmin(ans, max({sumW - subt[v], (*it), subt[v] - (*it)}) -
                       min({sumW - subt[v], (*it), subt[v] - (*it)}));
      }
      if (it != (*wset[v]).begin()) {
        --it;
        chmin(ans, max({sumW - subt[v], (*it), subt[v] - (*it)}) -
                       min({sumW - subt[v], (*it), subt[v] - (*it)}));
      }
    }
    wset[v]->insert(subt[v]);
  };
  calc_ans(calc_ans, 0, -1);
  cout << ans << '\n';
}