#include <fstream>
#include <vector>
#include <stack>
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 , MN;
int cost_nod[ 16004 ];
bool viz[ 16004 ];
vector < int > Q[ 16004 ];
stack < int > st;
int main()
{
	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;
	viz[1] = 1;
	st.push(1);
	MN = 1 << 30;
	solc = MN * (-1);
	sol = MN * (-1);
	while(!st.empty())
	{
		x = st.top();
		gasit = 0;
		while(!Q[x].empty())
		{
			if (!viz[Q[x].front()])
			{
				it = Q[x].begin();
				st.push(*it);
				viz[*it] = 1;
				s1 += cost_nod[*it];
				if (MN > s2)
					MN = s2;
				if (solc < s1 - MN)
					solc = s1 - MN;
				s2 += cost_nod[*it];
				Q[x].erase(Q[x].begin());
				gasit = 1;
				break;
			}
			else
				Q[x].erase(Q[x].begin());
		}
		if (!gasit)
			st.pop();
	}
	fout << solc << '\n';
	return 0;
}