#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define ln '\n'
const ll N = 2e5 + 5;
const ll LG = 20;
ll n, glit = 1, p[N], mx[LG][N], up[LG][N], where[N], sz[N];
vector<ll> adj[N];
ll dfs(ll u, ll par){
up[0][u] = par;
mx[0][glit] = u;
where[u] = glit++;
ll tot = 1;
for (auto v: adj[u]){
if (v == par) continue;
tot += dfs(v, u);
}
sz[where[u]] = tot;
return tot;
}
ll answer(ll l, ll r){
if (l > r) return 0;
ll lg = log2(r-l+1);
return p[mx[lg][l]] > p[mx[lg][r-(1<<lg)+1]]? mx[lg][l]: mx[lg][r-(1<<lg)+1];
}
bool is_ancestor(ll u, ll v){
return where[u] <= where[v] && where[v] <= where[u] + sz[where[u]] - 1;
}
ll lca(ll u, ll v){
if (is_ancestor(u, v)) return u;
if (is_ancestor(v, u)) return v;
for (ll i = LG-1; i >= 0; i--){
if (!is_ancestor(up[i][u], v)) u = up[i][u];
}
return up[0][u];
}
ll dist(ll u, ll v){
ll ances = lca(u, v);
ll ans = 0;
for (ll i = LG-1; i >= 0; i--){
if (!is_ancestor(up[i][u], ances)) {ans += (1 << i); u = up[i][u];}
if (!is_ancestor(up[i][v], ances)) {ans += (1 << i); v = up[i][v];}
}
return ans + (u != ances) + (v != ances);
}
ll f(ll u, ll tp, ll btm){
ll res = 0, nxt;
for (auto v: adj[u]){
if (v == up[0][u]) continue;
if (btm == -1) nxt = answer(where[v],
where[v] + sz[where[v]] - 1);
else nxt = max(answer(where[v], where[btm]-1),
answer(where[btm] + sz[where[btm]], where[v] + sz[where[v]]-1),
[&](ll x, ll y){return p[x] < p[y];});
if (nxt) res = max(res, dist(u, nxt) + f(nxt, v, btm));
}
nxt = max(answer(where[tp], where[u] - 1),
answer(where[u] + sz[where[u]], where[tp] + sz[where[tp]] - 1),
[&](ll x, ll y){return p[x] < p[y];});
if (nxt) res = max(res, dist(u, nxt) + f(nxt, tp, u));
return res;
}
void solve(){
cin >> n;
for (ll i = 1; i <= n; i++) cin >> p[i];
for (ll i = 0; i < n-1; i++){
ll u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
ll root = -1;
for (ll i = 1; i <= n; i++) if (p[i] == n) root = i;
dfs(root, root);
// for (ll i = 1; i <= n; i++) cout << where[i] << " ";
// cout << ln;
// for (ll i = 1; i <= n; i++) cout << sz[where[i]] << " ";
for (ll i = 1; i < LG; i++){
for (ll j = 1; j <= n; j++) up[i][j] = up[i-1][up[i-1][j]];
for (ll j = 1; j + (1 << (i-1)) <= n; j++){
mx[i][j] = (p[mx[i-1][j]] > p[mx[i-1][j + (1 << (i-1))]])? mx[i-1][j]: mx[i-1][j + (1 << (i-1))];
}
}
cout << f(root, root, -1) << ln;
// cout << where[1] << ' ' << where[1] + sz[where[1]] - 1 << ln;
// cout << answer(where[1], where[1] + sz[1] -1) << ln;
// for (ll i = 1; i <= n; i++) cout << mx[0][i] << ' ';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// ll TT; cin >> TT;
// while (TT--) {solve();}
solve();
}
