#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;

ifstream fin("asmax.in");
ofstream fout("asmax.out");

static const int NMAX  = 16005;
int n;
vector<int> v[NMAX];
vector<int> stack;
int val[NMAX];
int valMax;
bool visited[NMAX];

void Solve(int node)
{
    visited[node] = true;
    
    for(auto child : v[node])
    {
        if(!visited[child]){
            Solve(child);
            if(val[child] > 0)
                val[node]+= val[child];
            valMax = max(valMax,val[node]);
        }
    }
}

int main()
{
    fin >> n;
    for(int i =1; i<= n; ++i)
    {
        fin >> val[i];
    }
    int x, y;
    for(int i = 1; i< n; ++i)
    {
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    valMax= val[1];
    Solve(1);
    fout << valMax;
    return 0;
}