#include <bits/stdc++.h>

using namespace std;

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

const int Nmax=16001;
const int INF=20000000;

bitset<Nmax> visited;
forward_list<int> muchii[Nmax];
short int v[Nmax];

pair<int, bool> getSumMax(int node)
{
    visited[node]=1;
    vector<pair<int, bool>> sums;
    int vmax=-INF;
    int vmaxConc=-INF,indvmaxconc=-1;
    bool canConc=0;
    for(auto nxtnode : muchii[node])
    {
        if(visited[nxtnode]==0)
        {
            sums.push_back(getSumMax(nxtnode));
            if(vmax<sums.back().first)
            {
                vmax=sums.back().first;
                canConc=sums.back().second;
            }
            if(sums.back().second)
            {
                if(vmaxConc<sums.back().first)
                {
                    vmaxConc=sums.back().first;
                    indvmaxconc=sums.size()-1;
                }
            }
        }
    }
    if(sums.empty())
    {
        cout<<"getSumMax("<<node<<"): "<<v[node]<<' '<<1<<'\n';
        return make_pair(v[node], 1);
    }
    vmaxConc+=v[node];
    for(unsigned int i=0; i<sums.size(); i++)
    {
        if(!sums[i].second)
            continue;
        if(indvmaxconc==i)
            continue;
        if(sums[i].first>=0)
        {
            vmaxConc+=sums[i].first;
        }
    }

    int rez=v[node]; bool rezConc=1;
    if(rez<vmax)
    {
        rez=vmax;
        rezConc=canConc;
    }
    if(rez<vmax+v[node])
    {
        rez=vmax+v[node];
        rezConc=1;
    }
    if(rez<vmaxConc)
    {
        rez=vmaxConc;
        rezConc=1;
    }
    cout<<"getSumMax("<<node<<"): "<<rez<<' '<<rezConc<<'\n';
    return make_pair(rez, rezConc);
}


int main()
{
    int n;
    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;
        muchii[x].push_front(y);
        muchii[y].push_front(x);
    }
    fout<<getSumMax(1).first;
    return 0;
}