#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const ll I = 1000'000'000'000'000'000LL;
const int II = 2'000'000'000;
const ll M = 1000'000'007LL;
const int N = 1000'007;
int fau[N];
ll ans[N];
int per[N];
vector<int> ed[N];
int wys[N];
int jp[N][20];
int Find(int v)
{
if(fau[v] == v) return v;
return (fau[v] = Find(fau[v]));
}
void Union(int a, int b)
{
fau[Find(b)] = Find(a);
}
void DFS(int v)
{
for(int i = 1; i <= 19; ++i)
jp[v][i] = jp[jp[v][i - 1]][i - 1];
for(int i = 0; i < (int)ed[v].size(); ++i)
{
if(wys[ed[v][i]]) continue;
wys[ed[v][i]] = wys[v] + 1;
jp[ed[v][i]][0] = v;
DFS(ed[v][i]);
}
}
int Dis(int a, int b)
{
int ans = 0;
if(wys[a] < wys[b]) swap(a, b);
for(int i = 19; i >= 0; --i)
if(wys[jp[a][i]] >= wys[b])
{a = jp[a][i]; ans += (1<<i);}
for(int i = 19; i >= 0; --i)
if(jp[a][i] != jp[b][i])
{
a = jp[a][i]; b = jp[b][i];
ans += 2 * (1<<i);
}
if(a == b) return ans;
return ans + 2;
}
void Solve()
{
int n, a, b;
cin >> n;
for(int i = 1; i <= n; ++i)
cin >> per[i];
for(int i = 1; i < n; ++i)
{
cin >> a >> b; a = per[a]; b = per[b];
ed[a].pb(b); ed[b].pb(a);
}
wys[1] = 1;
DFS(1);
for(int v = 1; v <= n; ++v)
{
int ne;
fau[v] = v;
//cout << v << ":\n";
for(int j = 0; j < (int)ed[v].size(); ++j)
{
if(ed[v][j] > v) continue;
ne = Find(ed[v][j]);
//cout << "E: " << ed[v][j] << " " << ne << " " << Dis(ne, v) << "\n";
ans[v] = max(ans[v], ans[ne] + Dis(ne, v));
Union(v, ne);
}
}
cout << ans[n] << "\n";
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//int t; cin >> t;
//while(t--)
Solve();
return 0;
}
