// Programmer: Shadow1
#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using str = string; // yay python!
#define i64 int64_t
#define show(x) cerr << (#x) << " = " << (x) << '\n';
#define output_vector(v) for(auto &x : v){cout << x << ' ';}cout << '\n';
#define output_pairvector(v) for(auto &x : v){cout << x.first << " " << x.second << '\n';}
#define read_vector(v) for(auto &x : v){cin >> x;}
#define vt vector
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define pii pair<int,int>
#define fir first
#define sec second
#define sz(x) ll(x.size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define int long long
#define discretize(x) sort(x.begin(), x.end()); x.erase(unique(x.begin(), x.end()), x.end());
//
//
const int maxn = 2e5 + 5;
vector<int> depth(maxn), a(maxn), adj[maxn];
int twok[maxn][25]; //preset to -1
vector<int> p, ranks, set_size;
const int N = maxn;
void build() {
p.assign(N+2, 0);
ranks.assign(N+2, 0);
set_size.assign(N+2, 1);
for(int i=1; i<=N; ++i)
p[i] = i;
}
int find_set(int i) {
if(p[i] == i)
return i;
return p[i] = find_set(p[i]);
}
bool same(int i, int j) {
return find_set(i) == find_set(j);
}
void unite(int i, int j) {
if(same(i,j)) return;
int x = find_set(i), y = find_set(j);
if(ranks[x] > y)
swap(x,y);
p[x] = y;
if(ranks[x] == ranks[y])
++ranks[y];
set_size[y] += set_size[x];
}
int find_size(int x) {
return set_size[find_set(x)];
}
void dfs(int x, int p) {
for (int k = 0; k < 25; ++k) {
if (twok[x][k] == -1) break;
twok[x][k+1] = twok[twok[x][k]][k];
}
for (int it:adj[x]) {
if(it == p) continue;
twok[it][0] = x;
depth[it] = depth[x] + 1;
dfs(it,x);
}
}
int kpar(int x, int k){
for(int j=0; j<25; j++){
if(x==-1) break;
if(k&(1<<j)) x=twok[x][j];
}
return x;
}
int lca(int a,int b){
if (depth[a] < depth[b]) swap(a,b);
a = kpar(a, depth[a] - depth[b]);
if (a == b) return a; // edge case where b is an ancestor of a
for (int k=24;k>=0;k--){
if (twok[a][k] != twok[b][k]){
a = twok[a][k]; b = twok[b][k];
}
}
return twok[a][0];
}
int dist(int a, int b) {
return depth[a] + depth[b] - 2*depth[lca(a, b)];
}
void solve() {
int n;
cin >> n;
memset(twok, -1, sizeof(twok));
for(int i=1; i<=n; ++i)
cin >> a[i];
for(int i=0; i<n-1; ++i) {
int u, v;
cin >> u >> v;
adj[a[u]].push_back(a[v]);
adj[a[v]].push_back(a[u]);
}
build();
dfs(1, 0);
vector<int> dp(n+1);
for(int i=1; i<=n; ++i) {
for(auto &x : adj[i]) {
x = find_set(x);
if(x < i) {
p[x] = i;
dp[i] = max(dp[i], dp[x] + dist(i, x));
}
}
}
cout << dp[n] << '\n';
}
// CHECK YOUR OVERFLOWS!!!!
signed main() {
// freopen("output.txt", "w", stdout);
// freopen("input.txt", "r", stdin);
ios::sync_with_stdio(false);
cin.tie(NULL);
int T = 1;
// cin >> T;
for(int tc = 1; tc <= T; ++tc) {
// cout << "Case #" << tc << ": ";
solve();
}
return 0;
}
