#include <iostream>
#include <vector>
#include <fstream>

using namespace std;

vector <int> Muchii[16010];
int n,m = -20000,v[16010],viz[16010],poz;

int DFS(int nod)
{
    viz[nod] = 1;
    for(int i = 0; i < Muchii[nod].size(); ++i)
    {
        if(!viz[Muchii[nod][i]])
        {
            v[nod] += DFS(Muchii[nod][i]);
        }
    }
    if(v[nod] > 0)
        return v[nod];
    else
        return 0;
}

int main()
{
    fstream f("asmax.in", ios::in);
    fstream g("asmax.out", ios::out);
    f>>n;
    for(int i = 1; i <= n; ++i)
    {
        f>>v[i];
        if(v[i] > 0)
            poz = i;
        if(v[i] > m)
            m = v[i];
    }
    if(m <= 0)
        g<<m;
    else
    {
        for(int i = 1; i < n; ++i)
        {
            int x,y;
            f>>x>>y;
            Muchii[x].push_back(y);
            Muchii[y].push_back(x);
        }

        m = DFS(poz);
        for(int i = 1; i < n; ++i)
            if(m < v[i])
                m = v[i];
        g<<m;
    }


    return 0;
}