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

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

const int MAXN = 16011;

int N, M, cost[MAXN], sum[MAXN], sum_max = -MAXN;
vector <int> arb[MAXN];
bool used[MAXN];

void citire()
{
    int x, y;

    fin >> N;
    for ( int i = 1; i <= N; ++i)
        fin >> cost[i];
    for ( int i = 1; i < N; ++i)
    {
        fin >> x >> y;
        arb[x].push_back(y);
        arb[y].push_back(x);
    }
}

inline int maxim (int a, int b)
{
    if ( a < b )
        return b;
    return a;
}

inline void dfs(int nod)
{
    used[nod] = true;
    sum[nod] = cost[nod];

    for ( int i = 0; i < arb[nod].size(); ++i)
    {
        int y = arb[nod][i];
        if ( !used[y] )
        {
            dfs(y);
            if ( sum[y] > 0 )
                sum[nod] += sum[y];
            sum_max = maxim(sum_max, sum[nod]);
        }
    }
}

int main ()
{
    citire();

    dfs(1);

    fout << sum_max;

    fin.close();
    fout.close();

    return 0;
}