#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) (x).begin(),(x).end()
using namespace std;
typedef long long ll;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const ll MAX=2e5+10,P=1e9+7;
const ll INF=0x3f3f3f3f,oo=0x3f3f3f3f3f3f3f3f;
ll n;
ll p[MAX];
ll pid[MAX];
vector<int> G[MAX];
ll dp[MAX];
ll mx[MAX];
ll sz[MAX];
ll fa[MAX];
void init() {
for (int i=1;i<=n;i++) {
fa[i]=i;
sz[i]=1;
mx[i]=p[i];
}
}
int get(int a) {
return fa[a]=(fa[a]==a?a:get(fa[a]));
}
void unionn(int a,int b) {
a=get(a);b=get(b);
if (a==b) return;
if (sz[a]>sz[b]) swap(a,b);
fa[a]=b;
sz[b]+=sz[a];
mx[b]=max(mx[b],mx[a]);
}
ll up[MAX][20];
ll dep[MAX];
void dfs(int v,int p) {
up[v][0]=p;
for (int i=1;i<20;i++) up[v][i]=up[up[v][i-1]][i-1];
for (int i:G[v]) {
if (i==p) continue;
dep[i]=dep[v]+1;
dfs(i,v);
}
}
int jump(int v,int k) {
for (int i=19;i>=0;i--) {
// cout<<v<<" "<<k<<" "<<i<<"\n";
if (k&(1<<i)) v=up[v][i];
}
// cout<<v<<" fin\n";
return v;
}
ll dis(int a,int b) {
// cout<<a<<" "<<b<<" start\n";
// cout<<dep[a]<<" "<<dep[b]<<" dep\n";
if (dep[a]<dep[b]) swap(a,b);
ll ans=dep[a]-dep[b];
a=jump(a,dep[a]-dep[b]);
// cout<<a<<" "<<b<<" "<<ans<<"\n";;
if (a==b) return ans;
for (int i=19;i>=0;i--) {
if (up[a][i]!=up[b][i]) {
a=up[a][i];b=up[b][i];
ans+=2*(1<<i);
}
}
return ans+2;
}
int main() {
speed;
cin>>n;
for (int i=1;i<=n;i++) {
cin>>p[i];
pid[p[i]]=i;
}
for (int i=1;i<n;i++) {
int a,b;
cin>>a>>b;
G[a].push_back(b);
G[b].push_back(a);
}
init();
for (int i=0;i<20;i++) up[0][i]=0;
dep[1]=0;
dfs(1,0);
dp[1]=0;
for (int i=2;i<=n;i++) {
ll v=pid[i];
dp[i]=0;
for (int u:G[v]) {
if (p[u]<i) {
dp[i]=max(dp[i],dp[mx[get(u)]]+dis(pid[mx[get(u)]],v));
// cout<<pid[mx[get(u)]]<<" "<<v<<" "<<dis(pid[mx[get(u)]],v)<<"\n";
unionn(u,v);
}
}
// for (int i=1;i<=n;i++) cout<<p[i]<<" ";
// cout<<"\n";
}
// for (int i=1;i<=n;i++) cout<<dp[i]<<" ";
// cout<<"\n";
cout<<dp[n];
return 0;
}
