#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

const int N=16001;

vector <int> a[N];

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

int n,v[16001],m[16001][16001],suma[16001],summax,viz[16001];

void sum(int x)
{
    int y;
    viz[x]=1;
    suma[x]=v[x];
    for(int i=0; i<a[x].size(); i++)
    {
        y=a[x][i];
        if(!viz[y])
        {
            sum(y);
            if (suma[y] > 0)
            {
                suma[x] += suma[y];
            }
        }
    }
    if(suma[x]>summax)
        summax=suma[x];
}

void citire()
{
    in>>n;
    int x,y;
    for(int i=1; i<=n; i++)
        in>>v[i];
    for(int i=1; i<n; i++)
    {
        in>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    in.close();
}

int main()
{
    citire();
    sum(1);
    out<<summax;
    return 0;
}