#include <bits/stdc++.h>
using namespace std;
using ld = long double;
using ll = long long;
const int INF = 1e9, MOD = 1e9 + 7;
void solve();
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios::sync_with_stdio(false);
cin.tie(0);
int q = 1;
while (q--) {
solve();
}
}
vector<vector<ll>> g;
vector<ll> sz, par, used, lev;
vector<vector<ll>> ds, num;
vector<vector<ll>> l, r;
void get_sz(ll v, ll p) {
sz[v] = 1;
for (auto u : g[v]) {
if (u == p || used[u]) continue;
get_sz(u, v);
sz[v] += sz[u];
}
}
ll Find_centroid(ll v, ll p, ll all) {
ll next = -1;
for (auto u : g[v]) {
if (u == p || used[u]) continue;
if (sz[u] > all / 2) next = u;
}
if (next == -1) return v;
return Find_centroid(next, v, all);
}
vector<vector<ll>> cnt;
void calc(ll v, ll p, ll f, ll lv, ll lf, ll rf, ll c, ll& id) {
ds[lv][v] = f;
num[lv][v] = id++;
l[lv][v] = lf;
r[lv][v] = rf;
cnt[c].push_back(-INF);
for (auto u : g[v]) {
if (u == p || used[u]) continue;
calc(u, v, f + 1, lv, lf, rf, c, id);
}
}
void build(ll v, ll p, ll level) {
get_sz(v, -1);
v = Find_centroid(v, -1, sz[v]);
lev[v] = level;
par[v] = p;
used[v] = 1;
get_sz(v, -1);
ll id = 1;
ds[level][v] = 0;
num[level][v] = 0;
cnt[v].push_back(-INF);
for (auto u : g[v]) {
calc(u, -1, 1, level, id, id + sz[u] - 1, v, id);
}
for (auto u : g[v]) {
if (!used[u]) build(u, v, level + 1);
}
}
vector<ll> p, val;
vector<vector<ll>> del;
void upd(ll c, ll v, ll x) {
if (c == -1) return;
if (!del[lev[c]][v]) {
cnt[c][num[lev[c]][v]] = max(cnt[c][num[lev[c]][v]], x);
}
upd(par[c], v, x);
}
void solve() {
ll n; cin >> n;
p.resize(n), val.resize(n);
for (int i = 0; i < n; i++) {
cin >> val[i]; val[i]--;
p[val[i]] = i;
}
g.resize(n);
for (int i = 1; i < n; i++) {
ll a, b; cin >> a >> b;
a--, b--;
g[a].push_back(b);
g[b].push_back(a);
}
sz.resize(n), par.resize(n, -1),
used.resize(n), lev.resize(n);
ds.resize(20, vector<ll>(n));
num.resize(20, vector<ll>(n));
l.resize(20, vector<ll>(n));
r.resize(20, vector<ll>(n));
del.resize(20, vector<ll>(n));
cnt.resize(n);
build(0, -1, 0);
vector<ll> dp(n, -INF), cx(n, -INF);
dp[n - 1] = 0;
for (auto v : g[p[n - 1]]) {
cx[v] = 1;
upd(v, v, 1);
}
for (ll i = n - 2; i >= 0; i--) {
queue<ll> bfs;
bfs.push(p[i]);
vector<ll> dist(n, -1);
dist[p[i]] = 0;
while (!empty(bfs)) {
ll v = bfs.front(); bfs.pop();
dp[i] = max(dp[i], cx[v] + dist[v]);
for (auto u : g[v]) {
if (val[u] > i) continue;
if (dist[u] == -1) {
dist[u] = dist[v] + 1;
bfs.push(u);
}
}
}
for (auto v : g[p[i]]) {
cx[v] = max(cx[v], dp[i] + 1);
upd(v, v, dp[i] + 1);
}
}
ll ans = 0;
for (int i = 0; i < n; i++) {
ans = max(ans, dp[i]);
}
cout << ans;
}
