#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define yes() cout << "YES\n"
#define no() cout << "NO\n"
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
const int inf = 1e18;
const int mod = 1e9 + 7;
const int maxn = 1e7 + 5e6;
const int mod1 = 998244353;
const int mod2 = 1e18 + 1;
const int mod3 = 1e9 + 9;
const int mod4 = 333333333;
const int mod5 = 200000;
const int mod6 = 10007;
const int k = 300;
const int w = 1e5;
const ld EPS = 1e-8;
int LOG = 30;
vector<vector<int>> g;
vector<int> h;
vector<int> tin, tout;
vector<vector<int>> up;
vector<int> dp;
int timer = 1;
void precalc(int v, int p, int d) {
h[v] = d;
tin[v] = timer++;
up[v][0] = p;
for (int i = 1; i < LOG; i++) up[v][i] = up[up[v][i - 1]][i - 1];
for (int& u : g[v]) {
if (u != p) {
precalc(u, v, d + 1);
}
}
tout[v] = timer++;
}
bool anc(int a, int b) {
return tin[a] <= tin[b] && tout[b] <= tout[a];
}
int lca(int a, int b) {
if (anc(a, b)) return a;
if (anc(b, a)) return b;
for (int i = LOG - 1; i >= 0; i--) {
if (!anc(up[a][i], b)) a = up[a][i];
}
return up[a][0];
}
int get(int a, int b) {
int l = lca(a, b);
return h[a] + h[b] - 2 * h[l];
}
struct DSU {
vector<int> p, c;
int n;
DSU(vector<int>& b) {
n = b.size();
p.assign(n, 0);
c = b;
iota(all(p), 0ll);
}
int get(int x) {
if (p[x] == x) return x;
return p[x] = get(p[x]);
}
void unite(int a, int b) {
a = get(a), b = get(b);
if (a == b) return;
if (a < b) swap(a, b);
p[b] = a;
}
int get1(int x) {
x = get(x);
return c[x];
}
};
void solve() {
int n;
cin >> n;
vector<int> a(n);
for (int& i : a) cin >> i;
g.assign(n, vector<int> ());
dp.assign(n, 0);
tin.assign(n, 0);
tout.assign(n, 0);
h.assign(n, 0);
up.assign(n, vector<int> (LOG));
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--, v--;
u = a[u] - 1, v = a[v] - 1;
g[u].push_back(v), g[v].push_back(u);
}
precalc(0, 0, 0);
DSU dsu(a);
for (int v = 0; v < n; v++) {
for (int u : g[v]) {
u = dsu.get(u);
if (u < v) {
dp[v] = max(dp[v], dp[u] + get(u, v));
dsu.unite(u, v);
}
}
}
cout << dp.back() << "\n";
}
signed main() {
// cout.precision(16);
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1;
// cin >> t;
while (t--) {
solve();
}
}
