#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
vector <int> a[16001];
int v[16001],n,viz[16001],maxim=-1000000;
ifstream in("asmax.in");
ofstream out("asmax.out");
int smax(int x)
{
    int y,s=0;
    viz[x]=true;
    for(unsigned i=0;i<a[x].size();i++)
    {
        y=a[x][i];
        if(!viz[y])
            s=max(s,s+smax(y));
    }
    maxim=max(s+v[x],maxim);
    return s+v[x];
}
int main()
{
    int i,x,y;
    in>>n;
    for(i=1;i<=n;i++)
        in>>v[i];
    for(i=1;i<n;i++)
    {
        in>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    x=smax(1);
    out<<maxim;
    return 0;
}