#include <bits/stdc++.h>
using namespace std;
ifstream fin("asmax.in");
ofstream fout("asmax.out");
int n,cost[16010],d[16010],i,a,b,x,y,viz[16010],maxi;
vector<int>v[16010];
/*struct cmp  amintire
{
    bool operator()(int x,int y)
    {
        return d[x]<d[y];
    }
};
priority_queue<int,vector<int>,cmp>q;
*/
void rec(int nod)
{
    viz[nod]=1;
    if(v[nod].size())
        for(auto it:v[nod])
            if(!viz[it])
            {
                rec(it);
                viz[it]=1;
                d[nod]=max(0,max(d[nod],d[nod]+d[it]));
            }
    d[nod]=max(d[nod],0);
}
int main()
{
    fin>>n;
    for(i=1; i<=n; i++)
        fin>>cost[i], d[i]=cost[i];
    for(i=1; i<n; i++)
    {
        fin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    viz[1]=1;
    rec(1);
    /*while(!q.empty())         amintire
    {
        y=q.top();
        q.pop();
        for(auto it:v[y])
        {
            x=it;
            if(d[x]<d[x]+d[y] && d[x]+d[y]>=0)
            {
                d[x]+=d[y];
                q.push(x);
            }
            else if(d[x]<0)
                d[x]=0,q.push(x);
        }
    }
    */
    for(i=1; i<=n; i++)
        maxi=max(d[i],maxi);
    fout<<maxi;
    return 0;
}