#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];
int scor[Nmax];

void calcScoruri(int node=1)
{
    visited[node]=1;
    set<int> sums;
    for(auto nxtnode : muchii[node])
    {
        if(visited[nxtnode]==0)
        {
            calcScoruri(nxtnode);
            sums.insert(scor[nxtnode]);
        }
    }
    if(sums.empty())
    {
        scor[node]=v[node];
        return;
    }

    int vmaxCompus=-INF;
    for(auto i=sums.rbegin(); i!=sums.rend(); i++)
    {
        if(vmaxCompus==-INF)
        {
            vmaxCompus=*i;
            continue;
        }
        if(*i>0)
            vmaxCompus+=*i;
        else break;
    }

    scor[node]=max(0, vmaxCompus)+v[node];
    return;
}


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);
    }
    calcScoruri();
    int vmax=-INF;
    for(int i=1; i<=n; i++)
        vmax=max(vmax, scor[i]);
    fout<<vmax;
    return 0;
}