#include <algorithm>
#include <cassert>
#include <iostream>
#include <set>
#include <vector>

using namespace std;
using ll = long long;

#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define all(v) begin(v), end(v)

template <class T> bool chmin(T &dst, T src) {
  if (dst > src) {
    dst = src;
    return true;
  }
  return false;
}

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);

  int n;
  cin >> n;
  vector<int> w(n);
  rep(i, n) cin >> w[i];
  vector<vector<int>> graph(n);
  vector<pair<int, int>> edges(n - 1);
  rep(i, n - 1) {
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    graph[a].emplace_back(b);
    graph[b].emplace_back(a);
    edges[i] = {a, b};
  }

  ll ans = 1LL << 60;
  rep(i, n - 1) {
    for (int j = i + 1; j < n - 1; ++j) {
      set<int> remain;
      rep(k, n) remain.insert(k);

      auto dfs = [&](auto &&f, int v, int p) -> ll {
        remain.erase(v);
        ll sum = w[v];
        for (auto &c : graph[v]) {
          if (c == p) continue;
          if (edges[i] == pair{v, c} || edges[i] == pair{c, v}) continue;
          if (edges[j] == pair{v, c} || edges[j] == pair{c, v}) continue;
          sum += f(f, c, v);
        }
        return sum;
      };

      vector<ll> result;
      while (!remain.empty()) {
        result.push_back(dfs(dfs, *remain.begin(), -1));
      }
      assert(result.size() == 3);
      sort(all(result));
      chmin(ans, result.back() - result.front());
    }
  }
  cout << ans << endl;
}