#include <iostream>
#include <fstream>

using namespace std;

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

const int N = 16001;
int lst[N], vf[2*N], urm[2*N], v[N], smax[N], nr=0, smx=-16000000;
bool viz[N];

void Add(int x, int y);
void SMax(int i);

int main()
{
    int n;
    in >> n;
    for(int i=1; i<=n; i++)
    {
        in >> v[i];
    }
    for(int i=1; i<=n-1; i++)
    {
        int x, y;
        in >> x >> y;
        Add(x, y);
        Add(y, x);
    }

    SMax(1);

    out << smx;
    return 0;
}

void Add(int x, int y)
{
    nr++;
    vf[nr]=y;
    urm[nr]=lst[x];
    lst[x]=nr;
}

void SMax(int i)
{
    viz[i]=true;
    smax[i]=v[i];
    for(int p=lst[i];p && !viz[vf[p]]; p=urm[p])
    {
        SMax(vf[p]);
        smax[i]=max(smax[i], smax[i]+smax[vf[p]]);
    }
    smx=max(smx, smax[i]);
}