#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second
using namespace std;
typedef pair<int, int> pii;
const int MX = 200005;
int n;
int a[MX];
int e[MX];
int mx[MX];
int res[MX];
vector<int> G[MX];
void nhap(){
cin >> n;
for(int i=1; i<=n; i++) cin >> a[i];
for(int i=1; i<n; i++){
int u, v;
cin >> u >> v;
G[a[u]].push_back(a[v]);
G[a[v]].push_back(a[u]);
}
}
namespace HLD{
int h[MX];
int p[MX];
int numC[MX];
int heavy[MX];
int head[MX];
void dfs(int u){
numC[u] = 1;
h[u] = h[p[u]] + 1;
for(int v: G[u]) if(v != p[u]){
p[v] = u;
dfs(v);
numC[u] += numC[v];
if(numC[v] > numC[heavy[u]]) heavy[u] = v;
}
}
void decompose(int u, int he){
head[u] = he;
if(heavy[u]) decompose(heavy[u], he);
for(int v: G[u]) if(v != heavy[u] && v != p[u]){
decompose(v, v);
}
}
int dis(int u, int v){
int res = 0;
while(head[u] != head[v]){
if(h[head[u]] < h[head[v]]) swap(u, v);
res += h[u] - h[head[u]] + 1;
u = p[head[u]];
}
res += abs(h[u] - h[v]);
return res;
}
void build(){
dfs(1);
decompose(1, 1);
}
}
int fp(int u){
return e[u] < 0? u : e[u] = fp(e[u]);
}
void solve(){
HLD::build();
memset(e, -1, sizeof e);
memset(res, 0, sizeof res);
for(int i=1; i<=n; i++) mx[i] = i;
for(int u=1; u<=n; u++){
int best = 0;
for(int x: G[u]) if(x < u){
int v = fp(x);
best = max(best, res[v] + HLD::dis(u, mx[v]));
int t = fp(u);
if(e[t] > e[v]) swap(t, v);
e[v] += e[t];
e[t] = v;
}
int t = fp(u);
res[t] = best;
mx[t] = u;
}
cout << res[fp(n)];
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
nhap();
solve();
return 0;
}
