#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

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

const int INF = -1000000005;
const int DIM = 16005;

vector <int> G[DIM];

int n,x,y,Cost[DIM],ans=INF,viz[DIM];

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

void DFS(int nod)
{
    viz[nod]=1;
    vector <int> ::iterator it;
    for(it=G[nod].begin();it!=G[nod].end();it++)
    {
        if(!viz[*it])
        {
            DFS(*it);
            if(Cost[*it]>0)
                Cost[nod]+=Cost[*it];
        }
    }
    ans=max(ans,Cost[nod]);
}

int main()
{
    Read();
    DFS(1);
    fout<<ans<<'\n';
}