#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
const int da=16001;
ifstream f("asmax.in");
int v[da],vmax=-1001,suma=0,n,i;
int x,y;
bool viz[da];
vector <int> a[da];
void citire()
{
    f>>n;
    for( i=1; i<=n; i++)
    {
        f>>v[i];
        if(v[i]>vmax)
            vmax=v[i];
    }
    for(int i=1; i<n; i++)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
}

void parcurgere (int x)
{

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

}

int main()
{

    citire();
    parcurgere(1);
    ofstream g("asmax.out");
    vmax=-1001;
    for(i=1;i<=n;i++)
    {
        if(v[i]>vmax) vmax=v[i];
    }
    //cout<<vmax;
    g<<vmax;
    g.close();



    return 0;
}