#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 200'010;
const int lg = 20;
vector<int> A[N];
int val[N];
int anc[N][lg];
int height[N];
void dfs1(int v, int p, int h)
{
anc[v][0] = p;
Loop (i,0,lg-1)
anc[v][i+1] = anc[anc[v][i]][i];
height[v] = h;
for (int u : A[v])
if (u != p)
dfs1(u, v, h+1);
}
int lca(int v, int u)
{
if (height[v] < height[u])
swap(v, u);
int diff = height[v] - height[u];
Loop (i,0,lg)
if ((diff>>i)&1)
v = anc[v][i];
if (v == u)
return v;
LoopR (i,0,lg) {
if (anc[v][i] != anc[u][i]) {
v = anc[v][i];
u = anc[u][i];
}
}
return anc[v][0];
}
int dis(int v, int u)
{
return height[v] + height[u] - 2 * height[lca(v, u)];
}
namespace dsu {
int par[N];
int p2[N];
void init(int n) {
fill(par, par+n, -1);
fill(p2, p2+n, -1);
}
int rt(int v) { return p2[v] == -1? v: (p2[v] = rt(p2[v])); }
void unite(int v, int u) {
v = rt(v);
u = rt(u);
par[u] = v;
p2[u] = v;
}
}
vector<int> A2[N];
ll ans;
void dfs(int v, ll h)
{
ans = max(ans, h);
for (int u : A2[v])
dfs(u, h + dis(v, u));
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
int n;
cin >> n;
Loop (i,0,n)
cin >> val[i];
Loop (i,1,n) {
int v, u;
cin >> v >> u;
v = val[v-1]-1;
u = val[u-1]-1;
A[v].push_back(u);
A[u].push_back(v);
}
dfs1(0, 0, 0);
dsu::init(n);
Loop (v,0,n) {
for (int u : A[v]) {
if (v > u)
dsu::unite(v, u);
}
}
int rt = -1;
Loop (i,0,n) {
if (dsu::par[i] == -1)
rt = i;
else
A2[dsu::par[i]].push_back(i);
}
dfs(rt, 0);
cout << ans << '\n';
}
