#include <iostream>
#include <stdio.h>
#include <vector>
#define NMax 16003
using namespace std;
vector<int> Graf[NMax];
int v[32003],N,M,x,y,Max=-999999;
bool mark[NMax];

void Read()
{
    scanf("%d",&N);

    for(int i=1;i<=N;i++)
        scanf("%d",&v[i]);

    for(int i=1;i<N;i++)
    {
        scanf("%d%d",&x,&y);
        Graf[x].push_back(y);
        Graf[y].push_back(x);
    }
}

void DFS(int nod)
{
    mark[nod]=true;
    for(vector<int>::iterator it=Graf[nod].begin();it!=Graf[nod].end();it++)
        if(mark[*it]==false)
        {
            DFS(*it);
            v[nod]=max(v[nod],v[*it]+v[nod]);
        }
    Max=max(Max,v[nod]);
}

int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    Read();
    DFS(1);
    printf("%d ",Max);
}