#include <fstream>
#include <vector>
#include <stack>
#include <cstring>
#define INF 1<<30
using namespace std;
const char iname[] = "asmax.in";
const char oname[] = "asmax.out";
ifstream fin(iname);
ofstream fout(oname);
int N , M , i , j , x , y , comp_conexe , gasit , s1 , s2 , solc , sol;
int MN[ 16004 ];
int nr;
int cost_nod[ 16004 ];
bool viz[ 16004 ];
vector < int > Q[ 16004 ];
stack < int > st;
int main()
{
	memset(MN,INF,sizeof(MN));
	fin >> N;
	for (i = 1; i <= N; ++i)
		fin >> cost_nod[i];
	for (i = 1; i <= N-1; ++i)
		fin >> x >> y , Q[x].push_back(y) , Q[y].push_back(x);
	vector < int > :: iterator it;
	sol = (1<<30) * (-1);
	for (i = 1; i <= N; ++i)
	{
		solc = MN[i] * (-1);
		viz[i] = 1;
		st.push(i);
		s1 = s2 = 0;
		while(!st.empty())
		{
			x = st.top();
			gasit = 0;
			while(!Q[x].empty())
			{
				if (!viz[Q[x].front()])
				{
					it = Q[x].begin();
					++nr;
					st.push(*it);
					viz[*it] = 1;
					s1 += cost_nod[*it];
					if (MN[i] > s2)
						MN[i] = s2;
					if (solc < s1 - MN[i] && nr > 1)
						solc = s1 - MN[i];
					s2 += cost_nod[*it];
					Q[x].erase(Q[x].begin());
					gasit = 1;
					break;
				}
				else
					Q[x].erase(Q[x].begin());
			}
			if (!gasit)
				st.pop();
		}
		if (solc > sol)
			sol = solc;
		memset(viz,0,sizeof(viz));
		for (j = 1; j <= i; ++j)
			viz[j] = 1;
	}
	fout << sol << '\n';
	return 0;
}