#include <bits/stdc++.h>

using namespace std;

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

const int MAX = 16001;

int v[MAX], lst[MAX], urm[MAX * 2], vf[MAX * 2], result, nr;
bool viz[MAX];

void adauga(int x, int y)
{
    vf[++nr] = y;
    urm[nr] = lst[x];
    lst[x] = nr;
}

void dfs(int ind)
{
    viz[ind] = true;
    for(int p = lst[ind]; p != 0; p = urm[p])
    {
        int y = vf[p];
        if(!viz[y])
        {
            dfs(y);
            if(v[y] > 0)
            {
                v[ind] += v[y];
            }
        }
    }
}

int main()
{
    int x, y, n;
    in >> n;
    for(int i = 1; i <= n; i++)
    {
        in >> v[i];
    }
    for(int i = 1; i < n; i++)
    {
        in >> x >> y;
        adauga(x, y);
        adauga(y, x);
    }
    dfs(1);
    result = v[1];
    for(int i = 2; i <= n; i++)
    {
        result = result > v[i] ? result : v[i];
    }
    out << result;
    return 0;
}