#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=(j);i<=(k);i++)
#define for2(i,j,k) for(int i=(j);i>=(k);i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define bit(n,i) ((n>>i)&1)
#define all(x) x.begin(),x.end()
//#pragma GCC optimize("O2,unroll-loops")
//#pragma GCC target("avx,avx2,bmi,bmi2,sse,sse2,sse3,ssse3,sse4,popcnt")
#define int long long
typedef long long ll;
typedef pair<int,int> pii;
typedef long double ld;
typedef pair<ld,ld> pdd;
typedef pair<ll,ll> pll;
const ll maxn=2e5+69;
const ll offset=1e9;
const ll block_sz=317;
const ll inf=1e18;
const ll mod=123456789;
int n,p[maxn],par[maxn];
vector<int> adj[maxn];
int Find(int u)
{
return par[u]<0?u:par[u]=Find(par[u]);
}
int dep[maxn],up[maxn][21],in[maxn],out[maxn],Time,dp[maxn];
void dfs(int u,int pre)
{
in[u]=++Time;
up[u][0]=pre;
for1(i,1,20) up[u][i]=up[up[u][i-1]][i-1];
for(int v:adj[u])
{
if (v==pre) continue;
dep[v]=dep[u]+1;
dfs(v,u);
}
out[u]=Time;
}
bool is_ancestor(int u,int v)
{
return in[u]<=in[v] && out[v]<=out[u];
}
int lca(int u,int v)
{
if (is_ancestor(u,v)) return u;
if (is_ancestor(v,u)) return v;
for2(i,20,0) if (!is_ancestor(up[u][i],v)) u=up[u][i];
return up[u][0];
}
void sol()
{
cin >> n;
for1(i,1,n) cin >> p[i];
for1(i,1,n-1)
{
int u,v; cin>> u>> v;
u=p[u],v=p[v];
adj[u].pb(v);
adj[v].pb(u);
}
dfs(1,1);
for1(i,1,n) par[i]=-1;
for1(u,1,n)
{
for(int v:adj[u])
{
v=Find(v);
if (v<u)
{
par[v]=u;
dp[u]=max(dp[u],dp[v]+dep[u]+dep[v]-2*dep[lca(u,v)]);
}
}
}
cout << dp[n];
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// freopen("PAINT.inp","r",stdin);
// freopen("PAINT.out","w",stdout);
int t=1;//cin >> t;
while (t--)
{
sol();
}
}
/*
*/
