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

const int N = 16001;
vector <int> a[N];
int n, m, s[N], v[N];
bool viz[N];

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

void citire ()
{
    fin >> n ;
    for ( int i = 1 ; i <= n ; i++ )
    {
        fin >> v[i];
    }
    int x, y;
    for ( int i = 1 ; i < n ; i++ )
    {
        fin >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    fin.close();
}

void dfs ( int x )
{
    viz[x] = true;
    int y;
    s[x] += v[x];
    for ( int i = 0 ; i < a[x].size() ; i++ )
    {
        y = a[x][i];
        if ( !viz[y] )
        {
            dfs(y);
            if ( s[y] > 0 )
            {
                s[x] += s[y];
            }
        }
    }
}

int main()
{
    citire();
    dfs(1);
    int ma = -1001;
    for ( int i = 1 ; i <= n ; i++ )
    {
        ma = max(ma, s[i]);
    }
    fout << ma;
    return 0;
}