#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream fin("asmax.in");
ofstream fout("asmax.out");
const int Nmax=16005;
vector <int> G[Nmax];
int A[Nmax],N,maxx=-1000;

void Read()
{
    fin>>N;
    for(int i=1;i<=N;++i)
    {
        fin>>A[i];
    }
    for(int i=1;i<N;++i)
    {
        int x,y;
        fin>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }

}


void DFS(int Nod,int Father)
{
    for(unsigned int j=0;j<G[Nod].size();++j)
    {
        int Vecin=G[Nod][j];
        if(Vecin==Father)
        continue;
        else
        {
            DFS(Vecin,Nod);
            A[Nod]=max(A[Nod],A[Vecin]+A[Nod]);
        }

    }
}


int main()
{
    Read();
    DFS(1,0);

    for(int i=1;i<=N;++i)
         maxx=max(maxx,A[i]);
    fout<<maxx<<"\n";

    return 0;
}