#include <fstream>
#include <vector>
#define DIM 16005

using namespace std;

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

int n,i,x,y,sol,v[DIM],val[DIM],d[DIM];
vector<int> L[DIM];

void dfs(int nod)
{
    v[nod] = 1; d[nod] = val[nod];
    for (int i=0; i<L[nod].size(); i++)
    {
        int vecin = L[nod][i];
        if (!v[vecin])
        {
            dfs(vecin);
            if (d[vecin] > 0)
                d[nod] += d[vecin];
        }
    }
    sol = max(sol, d[nod]);
}

int main()
{
    fin >> n;
    for (i=1; i<=n; i++)
        fin >> val[i];
    for (i=1; i<=n-1; i++)
    {
        fin >> x >> y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    dfs(1);
    fout << sol;
    return 0;
}