#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N = 2e5;
ll v[N],pos[N];
vector <ll> e[N];
struct DSU{
ll parent,score,maxx,power;
}v2[N];
ll leader(ll node){
if(v2[node].parent == node){
return node;
}else{
v2[node].parent = leader(v2[node].parent);
return v2[node].parent;
}
}
void connect(ll a,ll b){
a = leader(a);
b = leader(b);
if(v2[a].power > v2[b].power)swap(a,b);
v2[a].parent = b;
v2[b].power+=v2[a].power;
v2[b].score = max(v2[b].score,v2[a].score);
if(v[v2[b].maxx] < v[v2[a].maxx]){
v2[b].maxx = v2[a].maxx;
}
}
ll p[N][20],dpth[N];
void dfs(ll node,ll parent = 0,ll d = 0){
p[node][0] = parent;
dpth[node] = d;
for(auto i:e[node]){
if(i == parent)continue;;
dfs(i,node,d + 1);
}
}
ll LCA(ll a,ll b){
if(dpth[a] > dpth[b])swap(a,b);
for(ll i = 19;i >= 0;i--){
if(dpth[b] - (1<<i) >= dpth[a]){
b = p[b][i];
}
}
for(ll i = 19;i >= 0;i--){
if(p[a][i] != p[b][i]){
b = p[b][i];
a = p[a][i];
}
}
if(a != b)return p[a][0];
return a;
}
ll fastp(ll node,ll nr){
for(ll i = 19;i >= 0;i--){
if(nr - (1<<i) >= 0){
nr-=(1<<i);
node = p[node][i];
}
}
return node;
}
ll dist(ll a,ll b){
return dpth[a] + dpth[b] - 2*dpth[LCA(a,b)];
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll n,i,u,w,j;
cin>>n;
for(i= 0;i < n;i++){
cin>>v[i];pos[--v[i]] = i;
}
for(i = 0;i < n - 1;i++){
cin>>u>>w;u--;w--;
e[u].push_back(w);
e[w].push_back(u);
}
dfs(0);
for(j = 1;j < 20;j++){
for(i = 0;i < n;i++){
p[i][j] = p[p[i][j - 1]][j - 1];
}
}
for(i = 0;i < n;i++)v2[i] = {i,0,i,i};
for(i = 0;i < n;i++){
ll score = 1;
for(auto j:e[pos[i]]){
if(v[pos[i]] > v[j]){
///good and fucked already
ll l = leader(j);
score = max(v2[l].score + dist(v2[l].maxx,pos[i]),score);
}
}
//cout<<pos[i]<<' '<<score<<'\n';
v2[pos[i]].score = score;
for(auto j:e[pos[i]]){
if(v[pos[i]] > v[j]){
connect(pos[i],j);
}
}
}
cout<<v2[leader(0)].score - 1;
return 0;
}
