#include<bits/stdc++.h>
using namespace std;
#define int long long
#define in pair<int, int>
#define f first
#define s second
#define pb push_back
#define pob pop_back
#define INF (int)1e17
#define MX (int)3e5+5
#define LOGM (int)18
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL)
vector<int> pa(MX, -1);
vector<int> woke(MX);
int leader(int u)
{
if(pa[u] < 0)
return u;
else
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];
woke[v] = max(woke[v], woke[u]);
pa[u] = v;
return;
}
vector<int> adj[MX];
int timer;
int lca[LOGM][MX];
vector<int> st(MX), en(MX), dep(MX);
void DFS(int u, int p, int lvl)
{
lca[0][u] = p;
st[u] = timer++;
dep[u] = lvl;
for(int v: adj[u])
{
if(v==p)
continue;
DFS(v, u, lvl+1);
}
en[u] = timer;
}
int lcaa(int u, int v)
{
if(dep[u] > dep[v])
swap(u, v);
if((st[u] <= st[v]) && (en[v] <= en[u]))
return u;
for(int i = LOGM-1; i >= 0; i--)
{
int k = lca[i][u];
if((st[k] <= st[v]) && (en[v] <= en[k]))
continue;
u = k;
}
return lca[0][u];
}
int dist(int u, int v)
{
return dep[u]+dep[v]-2*dep[lcaa(u, v)];
}
signed main()
{
fast();
int n;
cin >> n;
vector<int> a(n+1);
for(int i = 1; i <= n; i++)
cin >> a[i];
int m = n-1;
while(m--)
{
int u, v;
cin >> u >> v;
adj[a[u]].pb(a[v]);
adj[a[v]].pb(a[u]);
}
DFS(1, 1, 0);
for(int i = 1; i < LOGM; i++)
{
for(int u = 1; u <= n; u++)
lca[i][u] = lca[i-1][lca[i-1][u]];
}
vector<int> dp(n+1, 0);
woke[1] = 1;
for(int u = 2; u <= n; u++)
{
woke[u] = u;
for(int v: adj[u])
{
if(v > u)
continue;
dp[u] = max(dp[u], dp[woke[leader(v)]]+dist(u, woke[leader(v)]));
merge(u, v);
}
}
cout << dp[n] << "\n";
return 0;
}
