#include <bits/stdc++.h>
using namespace std;
#define all(fl) fl.begin(),fl.end()
#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 lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pli pair<long long,int>
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
#define int long long
const int maxn=2e5+9;
vector<int>a[maxn];
int b[maxn];
int rev[maxn];
long long ans=0;
int dep[maxn];
int st[maxn][19],jump[maxn][19];
vector<pii>d[maxn];
void dfs(int u,int par){
for (auto v:a[u]){
if (v==par)continue;
dep[v]=dep[u]+1;
st[v][0]=b[u];
jump[v][0]=u;
for1(i,1,18){
jump[v][i]=jump[jump[v][i-1]][i-1];
st[v][i]=max(st[v][i-1],st[jump[v][i-1]][i-1]);
}
if (dep[v]>0){
int mx=0;
int nv=v;
for2(j,18,0){
if (st[nv][j]==0)continue;
if (st[nv][j]<b[v]){
mx=max(mx,st[nv][j]);
nv=jump[nv][j];
}
}
if (mx>0)d[v].pb({rev[mx],dep[v]-dep[rev[mx]]});
nv=st[nv][0];
d[rev[nv]].pb({v,dep[v]-dep[rev[nv]]});
}
dfs(v,u);
}
}
long long f[maxn];
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin>>n;
for1(i,1,n){
cin>>b[i];
rev[b[i]]=i;
}
for1(i,1,n-1){
int u,v;
cin>>u>>v;
a[u].pb(v);
a[v].pb(u);
}
int root;
for1(i,1,n)if (b[i]==n)root=i;
dfs(root,0);
/*for1(i,1,n){
for (auto v:d[i]){
cout<<i<<" "<<v.fi<<" "<< v.se<<'\n';
}
}*/
for1(i,1,n){
for (auto v:d[rev[i]]){
f[rev[i]]=max(f[rev[i]],f[v.fi]+v.se);
}
ans=max(ans,f[rev[i]]);
}
cout<<ans;
}
