#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

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

const int MaxN = 16006;

int n;
int cost[MaxN];
bool vizitat[MaxN];
int rez;
vector <vector <int> > G;

void Dfs(int nod);

int main()
{
    fin >> n;
    G = vector<vector <int> > (n + 1);
    for (int i = 1; i <= n; ++i)
        fin >> cost[i];

    for (int i = 1; i < n; ++i)
    {
        int x, y;
        fin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

    Dfs(1);
    int rez = -10001;
    for (int i = 1; i <= n; ++i)
        rez = max(rez, cost[i]);

    fout << rez;
}

void Dfs(int nod)
{
    vizitat[nod] = true;
    for (int i = 0; i < G[nod].size(); ++i)
    {
        int vecin = G[nod][i];
        if (!vizitat[vecin])
        {
            Dfs(vecin);
            cost[nod] = max(cost[nod], cost[nod] + cost[vecin]);
        }
    }
}