#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<cmath>
#define ll long long
using namespace std;
const int maxn=500010;
ll a[maxn];
int n;
struct my
{
	int next,y;
}e[maxn*2];
int linkk[maxn],len;
ll ans;
void insert(int xx,int yy)
{
	e[++len].next=linkk[xx],linkk[xx]=len;
	e[len].y=yy;
}
void dfs(int x,int fa,int dis)
{
	ans=max(ans,dis+a[x]);
	for(int i=linkk[x];i;i=e[i].next)
	{
		int to=e[i].y;
		if(to==fa)	continue;
		dfs(x,to,dis+1);
	}
}
int main()
{
	freopen("gamebeta.in","r",stdin);
	freopen("gamebeta.out","w",stdout);
	cin>>n;
	for(int i=1;i<=n;i++)	scanf("%lld",&a[i]);
	for(int i=1;i<n;i++)
	{
		int a,b;
		scanf("%d%d",&a,&b);
		insert(a,b);
		insert(b,a);
	}
	ans=1LL*2*(n-1)+a[1];
	dfs(1,0,0);
	cout<<ans<<endl;
	return 0;
}