#include<stdio.h>
#include<vector>
#include<algorithm>
#include<queue>
#include<fstream>
#define maxn 16005



int maxim=-1<<30;
using namespace std;
vector<int> a[maxn];
bool uz[maxn];
int cost[maxn];
int n;
int grad[maxn];
queue<int> q;
ifstream in("asmax.in");
ofstream out("asmax.out");

void read()
{

    in>>n;
    for(int i=1;i<=n;i++)
        in>>cost[i];
    int x,y;
    for(int i=1;i<n;i++)
    {
        in>>x>>y;
        grad[x]++;
        grad[y]++;
        a[x].push_back(y);
        a[y].push_back(x);
    }
}

void solve()
{
    for(int i=1;i<=n;i++)
        if(grad[i]==1)
        {
            q.push(i);
            uz[i]==1;
            if(cost[i]>maxim) maxim=cost[i];
        }
        int cnt;
    while(!q.empty())
    {
        int nod=q.front();
        q.pop();
        uz[nod]=1;
        cnt=0;
        for(int i=0;i<a[nod].size();i++)
        {
            if(uz[a[nod][i]]==0)
            {
            cost[a[nod][i]]=max(cost[a[nod][i]],cost[a[nod][i]]+cost[nod]);
            if(cost[a[nod][i]]>maxim) maxim=cost[a[nod][i]];

            cnt=0;
            int nodc=a[nod][i];
            for(int j=0;j<a[nodc].size();j++)
            {
                if(uz[a[nodc][j]]==0) cnt++;
            }
            if(cnt==1) q.push(a[nod][i]);
            }
        }
    }
}

int main()
{
    freopen("asmax.out","w",stdout);
    read();
    solve();
    out<<maxim;
}