#include <bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define dbg(x) cerr<<#x": "<<(x)<<endl
#define dbg_p(x) cerr<<#x": "<<(x).first<<' '<<(x).second<<endl
#define dbg_v(x, n) {cerr<<#x"[]: ";for(long long _=0;_<n;++_)cerr<<(x)[_]<<' ';cerr<<endl;}
#define all(v) v.begin(), v.end()
#define fi first
#define se second

template<typename T1, typename T2>
ostream& operator <<(ostream &out, const pair<T1, T2> &item) {
	out << '(' << item.first << ", " << item.second << ')';
	return out;
}

template <typename T>
ostream& operator <<(ostream &out, const vector<T>& v) {
	for(const auto &item : v) out << item << ' ';
	return out;
}

#define Nmax 500005
int n,a[Nmax];
vector<int> v[Nmax],v2[Nmax];
pii b[Nmax];
int uz[Nmax];

void dfs(int nod, int ant, int h){
	a[nod] += h;
	for (auto it : v[nod]){
		if (it == ant) continue;
		v2[nod].push_back(it);
		dfs(it, nod, h+1);
	}
}

int dfs2(int nod){
	uz[nod] = 1;
	int x = 0;
	for (auto it : v2[nod]){
		x += dfs2(it);
	}
	return x;
}

bool OK(long long x){
	for (int i=1;i<=n;i++){
		// dbg(a[i]);
		if (a[i] > x) return 0;
		b[i].first = x - a[i];
		b[i].second = i;
		uz[i] = 0;
	}
	sort(b+1,b+n+1);
	// dbg_v(b+1,n);
	int p = 0;
	for (int i=1;i<=n;i++){
		if (!uz[b[i].second]){
			// dbg(p);
			// dbg(b[i]);
			p += dfs2(b[i].second);
			if (p > b[i].first) return 0;
			p++;
		}
	}
	return 1;
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin >> n;
	for (int i=1;i<=n;i++){
		cin >> a[i];
	}
	for (int i=1;i<n;i++){
		int x,y;
		cin >> x >> y;
		v[x].push_back(y);
		v[y].push_back(x);
	}
	dfs(1,-1,0);

	// OK(2);
	// return 0;
	long long p = 1, st = 0;
	for (;p<2e9;p<<=1);
	for (;p>=1;p>>=1){
		if (st + p <= 2e9 && !OK(st+p)) st+=p;
	}
	if (!OK(st)) st++;

	cout << st << '\n';

	return 0;
}