//####################
//CatExercise
//####################
#include<bits/stdc++.h>
#define int long long
using namespace std;
const int maxiN = 200001;
vector<int> links[maxiN];
int dp[maxiN];
const int LOG = 20;
int depth[maxiN];
long long up[maxiN][LOG];
void dfs(int node,int papa=-1,int deep=0){
up[node][0] = papa;
depth[node] = deep;
for(int v:links[node]){
if(papa==v)continue;
dfs(v,node,deep+1);
}
}
void computeUp(int n){
for(int l=1;l<LOG;l++){
for(int i = 0;i<n;i++){
if(up[i][l-1]==-1){
up[i][l]=-1;
}else{
up[i][l] = up[up[i][l-1]][l-1];
}
}
}
}
int jumpK(int a,int k){
for(int l=0;l<LOG;l++){
if((k>>l)&1){
a = up[a][l];
}
}
return a;
}
int lca(int a,int b){
if(depth[a]<depth[b])swap(a,b);
a = jumpK(a,depth[a]-depth[b]);
if(a==b){
return b;
}
for(int l=LOG-1;l>=0;l--){
if(up[a][l]!=up[b][l]){
a=up[a][l];
b=up[b][l];
}
}
return up[a][0];
}
int dist(int a,int b){
int LCA = lca(a,b);
return depth[a]+depth[b]-2*depth[LCA];
}
struct UnionFind{
vector<int> chef;
void init(int n){
chef.resize(n);
for(int i=0;i<n;i++){
chef[i]=i;
}
}
int find(int a){
if(a==chef[a])return a;
else return chef[a]=find(chef[a]);
}
void enraciner(int x,int r){
if(find(x)==find(r)){
return;
}else{
int fx = find(x);
int fy = find(r);
chef[fx] = fy;
}
}
};
signed main(){
int n;cin>>n;
int powers[n];
for(int i = 0;i<n;i++){
dp[i]=0;
cin>>powers[i];
powers[i]--;
}
for(int i= 0;i<n-1;i++){
int a,b;cin>>a>>b;
a--;b--;
links[powers[a]].push_back(powers[b]);
links[powers[b]].push_back(powers[a]);
}
dfs(0);
computeUp(n);
UnionFind UF;
UF.init(n);
for(int i = 0; i < n ; i++){
dp[i] = 0;
for(int voisin:links[i]){
if(voisin>i)continue;
int rep = UF.find(voisin);
dp[i] = max(dp[i], dp[rep]+dist(i,rep));
UF.enraciner(voisin,i);
}
}
cout<<dp[n-1]<<endl;
return 0;
};
