#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair <ll,ll> pll;
typedef pair <int,int> pii;
typedef pair <int,pii> piii;
#define forr(_a,_b,_c) for(int _a = (_b); _a <= int (_c); ++_a)
#define ford(_a,_b,_c) for(int _a = (_b) + 1; _a --> int (_c);)
#define forf(_a,_b,_c) for(int _a = (_b); _a < int (_c); ++_a)
#define st first
#define nd second
#define pb push_back
#define mp make_pair
#define all(x) begin(x),end(x)
#define mask(i) (1LL << (i))
#define bit(x, i) (((x) >> (i)) & 1)
#define bp __builtin_popcountll
#define file "test"
template<class X, class Y>
bool minz(X &x, const Y &y) {
if (x > y) {
x = y;
return true;
} return false;
}
template<class X, class Y>
bool maxz(X &x, const Y &y) {
if (x < y) {
x = y;
return true;
} return false;
}
const int N = 5e5 + 5;
const ll oo = (ll) 1e16;
const ll mod = 1e9 + 7; // 998244353;
int dep[N], up[20][N], par[N], sz[N], mx[N], a[N], u, v, n;
ll dp[N];
vector <int> g[N];
void dfs(int u){
for (int v : g[u]){
if (dep[v]) continue;
dep[v] = dep[u] + 1;
up[0][v] = u;
forr (i, 1, 17)
up[i][v] = up[i - 1][up[i - 1][v]];
dfs(v);
}
}
int lca (int u, int v){
if (dep[u] < dep[v]) swap(u, v);
int k = dep[u] - dep[v];
ford (i, 17, 0)
if (bit(k, i))
u = up[i][u];
if (u == v){
return u;
}
ford (i, 17, 0)
if (up[i][u] != up[i][v]){
u = up[i][u];
v = up[i][v];
}
return up[0][u];
}
int get (int u){
return u == par[u] ? u : par[u] = get(par[u]);
}
bool update (int u, int v){
u = get(u); v = get(v);
if (u == v) return 0;
if (sz[u] < sz[v]) swap(u, v);
par[v] = u;
sz[u] += sz[v];
maxz(mx[u], mx[v]);
return 1;
}
int dis (int u, int v){
return dep[u] + dep[v] - 2 * dep[lca(u, v)];
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef kaguya
freopen(file".inp", "r", stdin); freopen(file".out", "w", stdout);
#endif
cin >> n;
forr (i, 1, n){
cin >> a[i];
sz[i] = 1;
par[i] = i;
mx[i] = i;
}
forf (i, 1, n){
cin >> u >> v;
g[a[u]].pb(a[v]);
g[a[v]].pb(a[u]);
}
dep[1] = 1;
dfs(1);
forr (i, 1, n){
for (int v : g[i])
if (v < i){
int k = mx[get(v)];
maxz(dp[i], dp[k] + dis(i, k));
update(i, v);
}
}
cout << dp[n] << "\n";
return 0;
}
/*
*/
