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

ifstream fin("asmax.in");
ofstream fout("asmax.out");

int n;
int v[16005], dp[16005];
vector<int> a[16005];

void DFS(int x, int t)
{
    for (int e : a[x])
        if (e != t)
        {
            DFS(e, x);
            dp[x] = max({dp[x], dp[e] + v[x], dp[e] + dp[x]});
        }
}

int main()
{
    int x, y, sol;
    fin >> n;
    for (int i = 1; i <= n; i++)
    {
        fin >> v[i];
        dp[i] = v[i];
    }
    for (int i = 1; i < n; i++)
    {
        fin >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    sol = INT_MIN;
    DFS(1, 0);
    for (int i = 1; i <= n; i++)
        sol = max(sol, dp[i]);
    fout << sol << "\n";
    return 0;
}