#include <bits/stdc++.h>
using namespace std;
int const MAX=4e5+5;
int p[MAX];
int n;
vector<int>tree[MAX];
void read(){
cin>>n;
int i;
for(i=1;i<=n;++i)
cin>>p[i];
for(i=1;i<n;++i){
int u,v;
cin>>u>>v;
u=p[u];
v=p[v];
tree[u].push_back(v);
tree[v].push_back(u);
}
}
int euler[MAX];
int pos[MAX];
int h[MAX];
void dfs(int nod,int tata){
static int time=0;
euler[++time]=nod;
pos[nod]=time;
for(auto fiu : tree[nod])
if(fiu!=tata){
h[fiu]=h[nod]+1;
dfs(fiu,nod);
euler[++time]=nod;
}
}
int const LOG=20;
int rmq[MAX][LOG];
int loga[MAX];
void calc_rmq(){
int i;
for(i=1;i<2*n;++i)
rmq[i][0]=euler[i];
int j;
for(j=1;j<LOG;++j)
for(i=1;i<2*n;++i){
rmq[i][j]=rmq[i][j-1];
int nextpos=i+(1<<(j-1));
if(nextpos<2*n && h[rmq[i][j]]>h[rmq[nextpos][j-1]])
rmq[i][j]=rmq[nextpos][j-1];
}
for(i=2;i<MAX;++i)
loga[i]=loga[i/2]+1;
}
int lca(int nod1,int nod2){
int p1=pos[nod1];
int p2=pos[nod2];
if(p1>p2)
swap(p1,p2);
int len=p2-p1+1;
int logar=loga[len];
if(h[rmq[p1][logar]]<h[rmq[p2-(1<<logar)+1][logar]])
return rmq[p1][logar];
else
return rmq[p2-(1<<logar)+1][logar];
}
int dist(int nod1,int nod2){
return h[nod1]+h[nod2]-2*h[lca(nod1,nod2)];
}
struct DSU{
int n;
int tata[MAX];
void init(int n){
this->n=n;
}
int root(int nod){
if(tata[nod]){
int rt=root(tata[nod]);
tata[nod]=rt;
return rt;
}
return nod;
}
void uneste(int nod1,int nod2){
int root1=root(nod1);
int root2=root(nod2);
tata[root2]=root1;
}
}dsu;
long long ans[MAX];
void maxself(long long& x,long long val){
if(x<val)
x=val;
}
void solve(){
dsu.init(n);
int i;
for(i=1;i<=n;++i)
for(auto vec : tree[i])
if(vec<i){
int rt=dsu.root(vec);
maxself(ans[i],ans[rt]+dist(rt,i));
dsu.uneste(i,rt);
}
}
void write(long long ans){
cout<<ans;
}
int main()
{
read();
dfs(1,0);
calc_rmq();
solve();
write(ans[n]);
return 0;
}
