#include <iostream>
#include <vector>
#include <cstdio>
#include <bitset>
#include <algorithm>
#define NMAX 16005
using namespace std;

int n, v[NMAX],dp[NMAX];
vector<int> arb[NMAX];
bitset<NMAX> viz;

int max3(int a,int b,int c)
{
    return max(a,max(b,c));
}

void dfs(int x, int parent)
{
    viz[x]=1;
    if(!parent)
    {
        dp[x]=v[x];
        dfs(arb[x][0],x);

        return;
    }
    dp[x] = max3(dp[parent],v[x],v[x]+dp[parent]);
    for(vector<int>::iterator it = arb[x].begin();it!=arb[x].end();it++)
    {
        if(!viz[*it])
            dfs(*it,x);
    }
}

void solve()
{
    for(int i=1;i<=n;i++)
    {
        if(arb[i].size()==1)
        {
            dfs(2,0);
            return;
        }
    }
}

int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    scanf("%d ",&n);
    for(int i=1;i<=n;i++)
    {
        scanf("%d ",&v[i]);
    }
    for(int i=1;i<n;i++)
    {
        int a, b;
        scanf("%d %d ",&a,&b);
        arb[a].push_back(b);
        arb[b].push_back(a);
    }
    solve();
    int dpmax = dp[1];
    for(int i=2;i<=n;i++)
        dpmax=max(dpmax,dp[i]);
    printf("%d\n",dpmax);
    return 0;
}