#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MAXN = 2e5;
const int LOG = 20;
int lift[MAXN][LOG];
int depth[MAXN];
struct DSU {
vector<int> e;
DSU(int n) {
e = vector<int>(n, -1);
}
int get(int x) {
return e[x] < 0 ? x : e[x] = get(e[x]);
}
void unite(int x, int y) {
x = get(x);
y = get(y);
if (x == y) return;
if (x < y) swap(x, y);
e[x] += e[y];
e[y] = x;
}
};
int lca(int v, int u) {
if (depth[v] < depth[u]) swap(v, u);
int diff = depth[v] - depth[u];
for (int k = 0; k < LOG; ++k) {
if (diff >> k & 1) {
v = lift[v][k];
}
}
if (v == u) return v;
for (int k = LOG - 1; k >= 0; --k) {
if (lift[v][k] == -1) continue;
if (lift[v][k] != lift[u][k]) {
v = lift[v][k];
u = lift[u][k];
}
}
assert(lift[v][0] == lift[u][0]);
return lift[v][0];
}
int get_dist(int v, int u) {
int ancestor = lca(v, u);
return depth[v] + depth[u] - 2 * depth[ancestor];
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<int> a(n), ra(n + 1);
int root = -1;
vector<vector<int>> adj(n);
for (int i = 0; i < n; ++i) {
cin >> a[i];
ra[a[i]] = i;
if (a[i] == n) root = i;
}
for (int i = 1; i < n; ++i) {
int x, y;
cin >> x >> y;
--x; --y;
adj[x].push_back(y);
adj[y].push_back(x);
}
DSU dsu(n + 1);
auto dfs = [&](auto& dfs, int v, int p) -> void {
for (auto& u : adj[v]) {
if (u == p) continue;
depth[u] = depth[v] + 1;
dfs(dfs, u, v);
lift[u][0] = v;
}
};
for (auto& v : lift) for (auto& u : v) u = -1;
dfs(dfs, 0, -1);
for (int l = 1; l < LOG; ++l) {
for (int i = 0; i < n; ++i) {
if (lift[i][l - 1] == -1) continue;
lift[i][l] = lift[lift[i][l - 1]][l - 1];
}
}
//~ cerr << "a\n";
vector<ll> dp(n + 1);
for (int x = 1; x <= n; ++x) {
int i = ra[x];
ll res = 0;
for (auto& u : adj[i]) {
if (a[i] > a[u]) {
int mx = dsu.get(a[u]);
res = max(res, get_dist(i, ra[mx]) + dp[mx]);
//~ cerr << i << " -> " << u get_dist(i, u) << " " << dp[dsu.get(u)] << " " << res << "\n";;
dsu.unite(a[i], a[u]);
}
}
assert(dsu.get(x) == x);
dp[x] = res;
//~ for (int i = 1; i <= n; ++i) {
//~ cout << dp[dsu.get(i)] << " ";
//~ }
//~ cout << "\n";
}
cout << dp[n] << "\n";
}
