#include <fstream>
#include <vector>
#define dim 16001
using namespace std;
int f[dim], D[dim], vecin ,nod, i, n, v[dim], maxim, x, y;
vector <int> L[dim];
int dfs (int nod)
{
    f[nod]=1;
    D[nod]=v[nod];
    for (int i=0; i<L[nod].size(); i++)
    {
        int vecin =L[nod][i];
        if (f[vecin]==0)
        {
            dfs(vecin);
            if (D[vecin]>0)
                D[nod]+=D[vecin];
        }
    }
}
int main ()
{
    ifstream fin ("asmax.in");
    ofstream fout ("asmax.out");
    fin>>n;
    for (i=1; i<=n; i++)
        fin>>v[i];
    for (i=1; i<=n-1; i++)
    {
        fin>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    dfs(1);
    maxim=-2000000000;
    for (i=1; i<=n; i++)
        if (D[i]>maxim)
            maxim=D[i];
    fout<<maxim;
}