#include <algorithm>
#include <functional>
#include <iostream>
#include <utility>
#include <vector>
int main() {
    using namespace std;
    using lint = long long;

    int n;
    cin >> n;
    vector<lint> s(n);
    for (auto &e : s) cin >> e;

    vector g(n, vector<int>());
    for (int i = 0; i < n - 1; ++i) {
        int a, b;
        cin >> a >> b;
        a--;
        b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }

    const lint oo = 1e18;
    // [v]: v 以下

    vector dp(n, -oo);
    auto chmax = [](auto &x, auto y) { x = max(x, y); };

    auto dfs = [&](this auto self, int v) -> lint {
        if (dp[v] != -oo) return dp[v];
        lint ans = s[v];
        for (int nv : g[v]) {
            if (s[nv] > s[v]) {
                auto ansi = self(nv);
                chmax(ans, s[v] + ansi);
            }
        }
        return dp[v] = ans;
    };
    lint ans = -oo;
    for (int i = 0; i < n; ++i) chmax(ans, dfs(i));
    cout << ans << "\n";
}