#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ar array
#define debug(x) cerr << "[" << #x << "] = [" << x << "]\n"
template<class A, class B> ostream& operator<< (ostream& out, pair<A, B> p) {
return out << '[' << p.first << ", " << p.second << ']';
}
template<class T> ostream& operator<< (ostream& out, vector<T> v) {
out << '[';
for (int i = 0; i < v.size(); ++i) {
if (i > 0) {
out << ", ";
}
out << v[i];
}
return out << ']';
}
template<class T> ostream& operator<< (ostream& out, set<T> s) {
return out << (vector<T>(s.begin(), s.end()));
}
const int mxN = 100000;
int n, p[mxN], mx[mxN], offset[mxN];
ll ans = 0;
set<pair<int, int>> adj[mxN];
set<ar<int, 3>> small;
int find(int i) {
return i ^ p[i] ? p[i] = find(p[i]) : i;
}
void merge(int a, int b) {
if (adj[a].size() < adj[b].size()) swap(a, b);
p[b] = a;
if (mx[a] >= mx[b]) {
for (const pair<int, int>& p : adj[b]) {
if (find(a) != find(p.second))
adj[a].emplace(p.first + offset[b] - offset[a] + mx[a] - mx[b], p.second);
}
}
else {
offset[a] += mx[b] - mx[a];
for (const pair<int, int>& p : adj[b]) {
if (find(a) != find(p.second))
adj[a].emplace(p.first + offset[b] - offset[a], p.second);
}
}
set<pair<int, int>>().swap(adj[b]);
mx[a] = max(mx[a], mx[b]);
while(!adj[a].empty()) {
pair<int, int> p = *adj[a].begin();
if (find(p.second) != a && mx[a] + mx[find(p.second)] - offset[a] == p.first) break;
adj[a].erase(adj[a].begin());
if (find(p.second) != a) adj[a].emplace(mx[a] + mx[find(p.second)] - offset[a], find(p.second));
}
//debug(offset[a]);
//debug(adj[a]);
if (!adj[a].empty()) {
pair<int, int> p = *adj[a].begin();
assert(p.first + offset[a] == mx[a] + mx[find(p.second)]);
small.insert({p.first + offset[a], a, p.second});
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n;
for (int i = 0; i < n; ++i) {
cin >> mx[i];
p[i] = i;
}
for (int i = 1; i < n; ++i) {
int a, b; cin >> a >> b, --a, --b;
adj[a].emplace(mx[a] + mx[b], b);
adj[b].emplace(mx[a] + mx[b], a);
small.insert({mx[a] + mx[b], a, b});
}
while(!small.empty()) {
ar<int, 3> t = *small.begin(); small.erase(small.begin());
int a = find(t[1]), b = find(t[2]);
if (a == b || t[0] != mx[a] + mx[b]) continue; // fraud...
//cerr << a << " " << b << "\n";
ans += t[0];
assert(!adj[a].empty() && !adj[b].empty());
merge(a, b);
}
cout << ans;
return 0;
}
