#include <fstream>
#include <vector>
using namespace std;
const char iname[] = "asmax.in";
const char oname[] = "asmax.out";
ifstream fin(iname);
ofstream fout(oname);
int N , i , j , x , y , s1 , s2 , solc , sol;
int cn[ 16004 ];
vector < int > v[ 16004 ];
int MN = 1 << 30;
bool mark[ 16004 ];
int DFS(int nod)
{
	int sum = 0;
    mark[ nod ] = true;
    if (MN > s2)
        MN = s2;
    //if (solc < s1 - MN)
    //    solc = s1 - MN;
    s2 += cn[nod];
    vector < int > :: iterator it;
    for (it = v[nod].begin(); it != v[nod].end(); ++it)
    {
        if (!mark[*it])
		{
			int val = DFS(*it);
			if (val > 0)
				sum += val;
		}
	}
	sum += cn[nod];
	if (solc < sum) solc = sum;
	return sum;
}
int main()
{
    fin >> N;
    for (i = 1; i <= N; ++i)
        fin >> cn[i];
    for (i = 1; i <= N-1; ++i)
    {
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    sol = MN * (-1);
    for (i = 1; i <= N; ++i)
    {
        if (!mark[i])
        {
            MN = 1 << 30;
            solc = MN * (-1);
            s1 = s2 = 0;
            DFS(i);
            if (solc > sol)
                sol = solc;
        }
    }
    fout << sol << '\n';
    return 0;
}