#include <bits/stdc++.h>
#define ll long long
using namespace std;
ifstream fin ("asmax.in");
ofstream fout ("asmax.out");
int n, nodeValue[16005], totalValue[16005];
vector<int> tree[16005];

void findValue(int node, int &maxPos) {
    if (totalValue[node] > totalValue[maxPos])
        maxPos = node;

    for (int it : tree[node]) {
        if (!totalValue[it]) {
            totalValue[it] = totalValue[node] + nodeValue[it];
            findValue(it, maxPos);
        }
    }
}

int main() {
    fin.tie(0);
    fout.tie(0);
    ios::sync_with_stdio(0);
    fin >> n;
    for (int i = 1; i <= n; i++)
        fin >> nodeValue[i];
    int a, b;
    for (int i = 1; i < n; i++) {
        fin >> a >> b;
        tree[a].push_back(b);
        tree[b].push_back(a);
    }

    int maxPos = 1, minPos = 1;
    totalValue[1] = nodeValue[1];
    findValue(1, maxPos);

    for (int i = 2; i < maxPos; i++)
        if (totalValue[i] < totalValue[minPos])
            minPos = i;

    fout << totalValue[maxPos] - totalValue[minPos] + 1;
    return 0;
}