#include<bits/stdc++.h>
using namespace std;
#define int long long
#define in array<int, 2>
#define pb push_back
#define pob pop_back
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL)
const int MX = 2e5+5;
const int INF = 1e17;
const int LOGM = 18;
vector<int> adj[MX];
int par[LOGM][MX]; int dp[MX]; int dep[MX]; int tin[MX]; int tout[MX];
int T;
void dfs(int u, int p)
{
tin[u] = ++T;
par[0][u] = p;
dep[u] = dep[p]+1;
for(int v: adj[u])
{
if(v == p)
continue;
dfs(v, u);
}
tout[u] = T;
return;
}
int dist(int u, int v)
{
if(tin[u] > tin[v])
swap(u, v);
if(tout[u] >= tout[v])
return dep[v]-dep[u];
int s = u;
for(int i = LOGM-1; i >= 0; i--)
{
if(tout[par[i][s]] < tout[v])
s = par[i][s];
}
s = par[0][s];
return dep[u]+dep[v]-2*dep[s];
}
vector<int> bst(MX);
vector<int> pa(MX, -1);
int leader(int u)
{
if(pa[u] < 0)
return u;
return pa[u] = leader(pa[u]);
}
void merge(int u, int v)
{
u = leader(u);
v = leader(v);
if(u == v)
return;
if(pa[u] < pa[v])
swap(u, v);
pa[v]+=pa[u];
bst[v] = max(bst[v], bst[u]);
pa[u] = v;
return;
}
signed main()
{
fast();
int n; cin >> n;
vector<int> p(n+1);
for(int i = 1; i <= n; i++)
cin >> p[i];
for(int i = 1; i < n; i++)
{
int u, v; cin >> u >> v;
u = p[u]; v = p[v];
adj[u].pb(v); adj[v].pb(u);
}
par[0][0] = 0; dep[0] = 0; tout[0] = n+5;
dfs(1, 0);
for(int i = 1; i < LOGM; i++)
{
for(int u = 1; u <= n; u++)
par[i][u] = par[i-1][par[i-1][u]];
}
for(int i = 1; i <= n; i++)
bst[i] = i;
for(int i = 1; i <= n; i++)
{
for(int j: adj[i])
{
if(j < i)
{
int w = bst[leader(j)];
dp[i] = max(dp[i], dp[w]+dist(i, w));
merge(i, j);
}
}
}
cout << dp[n] << "\n";
return 0;
}
