#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#define watch(x) cout<<(#x)<<"="<<(x)<<'\n'
#define mset(d,val) memset(d,val,sizeof(d))
#define cbug if(DEBUG) cout
#define setp(x) cout<<fixed<<setprecision(x)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define forn(i,a,b) for(int i=(a);i<(b);i++)
#define fore(i,a,b) for(int i=(a);i<=(b);i++)
#define pb push_back
#define F first
#define S second
#define fbo find_by_order
#define ook order_of_key
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
//template<typename T>
//using pbds = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
void SD(int t=0){ cout<<"PASSED "<<t<<endl; }
ostream& operator<<(ostream &out, ii x){ out<<"("<<x.F<<","<<x.S<<")"; return out; }
template<typename T> void amax(T &a, T b){ a=max(a,b); }
template<typename T> void amin(T &a, T b){ a=min(a,b); }
struct Hash {
static uint64_t splitmix64(uint64_t x) {
// http://xorshift.di.unimi.it/splitmix64.c
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
};
const ll INF = ll(1e18);
const int MOD = 998244353;
const bool DEBUG = 0;
const int MAXN = 200005;
const int LG = 21;
struct DSU {
struct Node{ int p, sz, mx; };
vector<Node> dsu; int cc;
Node& operator[](int id){ return dsu[rt(id)]; }
DSU(int n){ dsu.resize(n);
forn(i,0,n){ cc=n; dsu[i]={i,1,i}; }
}
inline int rt(int u){ return (dsu[u].p==u) ? u : dsu[u].p=rt(dsu[u].p); }
inline bool sameset(int u, int v){ return rt(u)==rt(v); }
void merge(int u, int v){
u = rt(u); v = rt(v);
if(u == v) return;
if(dsu[u].sz < dsu[v].sz) swap(u,v);
dsu[v].p = u;
dsu[u].sz += dsu[v].sz;
dsu[u].mx = max(dsu[u].mx, dsu[v].mx);
cc--;
}
};
vector<vector<int>> adj;
vector<ll> dist;
vector<ll> dp;
vector<bool> vst;
int in[MAXN],out[MAXN],tmr=-1;
int prt[LG][MAXN];
int dep[MAXN];
void dfs_lca(int u, int p)
{
in[u]=++tmr;
prt[0][u]=p;
forn(i,1,LG){
if(prt[i-1][u]!=-1) prt[i][u]=prt[i-1][prt[i-1][u]];
}
for(int v: adj[u]){
if(v==p) continue;
dep[v] = dep[u] + 1;
dfs_lca(v,u);
}
out[u]=tmr;
}
bool isChild(int u, int v)
{
return in[u]<=in[v] && out[v]<=out[u];
}
int getLca(int u, int v)
{
if(isChild(u,v)) return u;
for(int i=LG-1;i>=0;i--){
if(prt[i][u]!=-1 && !isChild(prt[i][u],v))
u=prt[i][u];
}
return prt[0][u];
}
int main()
{
cin.tie(0)->sync_with_stdio(0);
mset(prt,-1);
int n; cin>>n;
adj.resize(n);
dp.resize(n, 0);
vst.resize(n, 0);
dist.resize(n);
int p[n];
forn(i,0,n)
{
cin>>p[i];
p[i]--;
}
forn(i,0,n-1)
{
int u,v; cin>>u>>v; u--; v--;
u=p[u];
v=p[v];
adj[u].pb(v);
adj[v].pb(u);
}
dfs_lca(0, -1);
DSU dsu(n);
forn(u,0,n)
{
for (int v : adj[u])
{
if (v > u) continue;
int mx = dsu[v].mx;
int dist = dep[u] + dep[mx] - 2 * dep[getLca(u, mx)];
dp[u] = max(dp[u], dp[mx] + dist);
}
for (int v : adj[u])
{
if (v > u) continue;
dsu.merge(u, v);
}
}
cout<<dp[n-1]<<'\n';
return 0;
}
