#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
vector<int> legaturi [16001];
int valori[16001],maxim=-100001;
bool evarf[16001];
int rezolva(int x)
{
    int i,t,f;
    t=valori[x];
    if (t>maxim){maxim=t;}
    for (i=0;i<legaturi[x].size();i++)
    {
     f=rezolva(legaturi[x][i]);
     if (f>0)
     {
         t+=f;
         if (t>maxim){maxim=t;}
     }
    }
    if (t<0){return 0;}
    else {return t;}
}
int main()
{
    ifstream in("asmax.in");
    ofstream out("asmax.out");
    int i,n,x,y;
    in>>n;
    for (i=1;i<=n;i++)
    {
        in>>valori[i];
        evarf[i]=true;
        if (valori[i]>maxim)
        {
            maxim=valori[i];
        }
    }
    for (i=1;i<n;i++)
    {
        in>>x;
        in>>y;
        legaturi[x].push_back(y);
        evarf[y]=false;
    }
    for (i=1;i<=n;i++)
    {
        if (evarf[i]==true)
        {
            x=i;
            break;
        }
    }
    rezolva(x);
    out<<maxim;
}