// Made by ordinary newbie
#pragma region setup
#include <bits/stdc++.h>
#include <random>
#include <chrono>
using namespace std;
// variables
#define int long long
using ld = long double;
using ll = long long;
using ull = unsigned long long;
template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
// bitwise operations
#define cnt_bit(n) __builtin_popcountll(n)
#define low_bit(n) ((n) & (-(n)))
#define bit(n, i) (((n) >> (i)) & 1)
#define set_bit(n, i) ((n) | (1ll << (i)))
#define reset_bit(n, i) ((n) & ~(1ll << (i)))
#define flip_bit(n, i) ((n) ^ (1ll << (i)))
// math
#define sqr(n) ((n) * (n))
int log2_floor(ull n) {
return n ? __builtin_clzll(1) - __builtin_clzll(n) : -1;
}
const ll INF = 1e18;
// utils
#define len(x) (int) x.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
for(auto& el : v) {
is >> el;
}
return is;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
for (int i = 0; i < len(v); i++) {
if (i) os << ' ';
os << v[i];
}
return os;
}
template<class... Args>
auto create(size_t n, Args&&... args) {
if constexpr(sizeof...(args) == 1) {
return vector(n, args...);
}
else {
return vector(n, create(args...));
}
}
struct custom_hash {
static uint64_t splitmix64(uint64_t x) {
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);
}
size_t operator()(pair<int, int> x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x.first + FIXED_RANDOM) ^ splitmix64(x.second + FIXED_RANDOM);
}
};
template<typename T, typename U>
bool chmin(T& a, const U b) {
if (b < a) {
a = b;
return true;
}
return false;
}
template<typename T, typename U>
bool chmax(T& a, const U b) {
if (b > a) {
a = b;
return true;
}
return false;
}
template<typename T>
void compress(vector<T>& v) {
int n = len(v);
vector<pair<T, int>> u(n);
for (int i = 0; i < n; i++) {
u[i] = {v[i], i};
}
sort(all(u));
int curr = 0;
for (int i = 0; i < n; i++) {
if (i != 0 && u[i].first != u[i - 1].first) curr++;
v[u[i].second] = curr;
}
}
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
#pragma endregion
struct DSU {
int n;
vector<int> p;
DSU(int N) {
n = N;
p.resize(n);
iota(all(p), 0);
}
int get(int v) {
if (p[v] == v) return v;
return p[v] = get(p[v]);
}
bool unite(int v, int u) {
v = get(v), u = get(u);
if (v == u) return false;
p[v] = u;
return true;
}
};
const int L = 20;
void solve() {
int n;
cin >> n;
vector<int> p(n);
cin >> p;
vector<int> pi(n);
for (int i = 0; i < n; i++) {
pi[p[i] - 1] = i;
}
vector<vector<int>> g(n);
for (int i = 0; i < n - 1; i++) {
int v, u;
cin >> v >> u;
v--, u--;
g[v].push_back(u);
g[u].push_back(v);
}
vector<int> tin(n), tout(n), depth(n, 0);
vector binup = create(n, L, 0);
int timer = 0;
function<void(int, int)> dfs = [&] (int v, int pr) {
binup[v][0] = pr;
for (int i = 1; i < L; i++) {
binup[v][i] = binup[binup[v][i - 1]][i - 1];
}
tin[v] = timer++;
for (int u : g[v]) {
if (u == pr) continue;
depth[u] = depth[v] + 1;
dfs(u, v);
}
tout[v] = timer;
};
dfs(0, 0);
auto is_pr = [&] (int pr, int v) {
return tin[pr] <= tin[v] && tout[v] <= tout[pr];
};
auto dist = [&] (int v, int u) {
int w = v;
for (int i = L - 1; i >= 0; i--) {
if (!is_pr(binup[w][i], u)) {
w = binup[w][i];
}
}
if (!is_pr(w, u)) {
w = binup[w][0];
}
return depth[v] + depth[u] - 2 * depth[w];
};
vector<int> dp(n, -1);
DSU dsu(n);
for (int v : pi) {
dp[v] = 0;
for (int u : g[v]) {
if (dp[u] == -1) continue;
u = dsu.get(u);
chmax(dp[v], dp[u] + dist(v, u));
dsu.unite(u, v);
}
}
cout << dp[pi.back()] << '\n';
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int tt = 1;
//cin >> tt;
for (int i = 1; i <= tt; i++) {
solve();
}
}
