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

int main(){
    int N;
    cin >> N;
    vector<int> A(N);
    for (int& x : A) cin >> x;

    vector<vector<int>> G(N);
    for (int i = 1; i < N; i++){
        int u, v;
        cin >> u >> v;
        u--, v--;
        if (A[u] > A[v]) G[u].push_back(v);
        if (A[v] > A[u]) G[v].push_back(u);
    }

    vector<ll> dp(N, 0);
    vector<bool> vis(N, false);
    auto dfs = [&](auto&& self, int n) -> ll{
        if (vis[n]) return dp[n];
        dp[n] = A[n], vis[n] = true;
        for (int v : G[n]) dp[n] = max(dp[n], self(self, v)+A[n]);
        return dp[n];
    };

    ll ans = 0;
    for (int i = 0; i < N; i++) ans = max(ans, dfs(dfs, i));
    cout << ans << endl;
}