#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
using namespace std;
ifstream in("asmax.in");
ofstream out("asmax.out");
const int N=16001;
vector<int> a[N];
queue<int> q;
int n,d[N],s[N],smax;
void bfs(int x0)
{
    int x,y,sc=0;
    q.push(x0);
    while(!q.empty())
    {
        x=q.front();
        q.pop();
        for(size_t i=0;i<a[x].size();i++)
        {
            if (sc<0)
            {
            sc=d[a[x][i]];

            }
            else sc+=d[a[x][i]];
            if (sc>smax)
                smax=sc;
        }
    }
}
void citire()
{
    int x,y;
    in>>n;
    for(int i=1;i<=n;i++)
        in>>d[i];
    for(int i=1;i<n;i++)
    {
        in>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
}
int main()
{
    citire();
    bfs(1);
    out<<smax;
    return 0;
}