#include <fstream>
#include <vector>
using namespace std;
#define dmax 16001
vector <int > v[dmax];
int n, use[dmax], val[dmax];
int smax=-9999999;
int maxv=-99999;

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

void read()
{
    int a, b;
    fin>>n;

    for(int i=1; i<=n; i++)
        {fin>>val[i];
        if(val[i]>maxv)
            maxv=val[i];

        }
    for(int i=1; i<n; i++)
    {
        fin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
}

int cut_tree(int vf)
{
    int k=0, vfg=0;
    use[vf]=1;

        for(int i=0; i<v[vf].size(); i++)
        {
            int y=v[vf][i];
            if(use[y]==0)
                    {vfg=cut_tree(y);
                    k=cut_tree(y);k+vfg;if(vfg>smax)
    smax=k;}

        }


        if(k+val[vf]>0)
            return k+val[vf];
            else return 0;

}

int main()
{
    read();

cut_tree(1);
if(smax)
fout<<smax<<'\n';
else fout<<maxv<<'\n';

    return 0;
}