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

using namespace std;

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

const int N=1000001;
vector <int> a[N];
int n, s[N], viz[N], rez = -1000000000;

void citire();
void dfs (int x);

int main()
{
    int i;
    citire();
    dfs(1);
    g<<rez;
    return 0;
}

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

void dfs(int x)
{
    viz[x]=true;
    int m=a[x].size();
    for (int i=0; i<m; i++)
    {
        int y=a[x][i];
        if (viz[y]==false)
        {
            dfs(y);
            if (s[y]>0)
            {
                s[x]+=s[y];
            }
        }
    }
    rez=max(rez, s[x]);
}