#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
using pii=pair<int,int>;
#define f first
#define s second
#define pb push_back
#define REP(i,n) for(int i=0;i<n;i++)
#define REP1(i,n) for(int i=1;i<=n;i++)
#define FILL(n,x) memset(n,x,sizeof(n))
#define ALL(_a) _a.begin(),_a.end()
#define sz(x) (int)x.size()
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()),c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
const ll maxn=5e5+5;
const ll maxlg=__lg(maxn)+2;
const ll INF64=4e18;
const int INF=0x3f3f3f3f;
const int MOD=1e9+7;
const ld PI=acos(-1);
const ld eps=1e-4;
#define lowb(x) x&(-x)
#define MNTO(x,y) x=min(x,(__typeof__(x))y)
#define MXTO(x,y) x=max(x,(__typeof__(x))y)
vector<int> g[maxn];
vector<pii> v;
ll dp[maxn];
int arr[maxn];
int dep[maxn];
struct uf{
int par[maxn],rank1[maxn],mx[maxn];
void init(int n){
REP(i,n) par[i]=i,rank1[i]=1,mx[i]=i;
}
int find(int u){
if(par[u]==u) return u;
return par[u]=find(par[u]);
}
void merge(int a,int b){
a=find(a),b=find(b);
if(a==b) return;
if(rank1[a]>rank1[b]) swap(a,b);
rank1[b]+=rank1[a];
par[a]=b;
if(arr[mx[a]]>arr[mx[b]]) mx[b]=mx[a];
}
}uf;
int par[maxn][20];
void dfs(int u,int p){
par[u][0]=p;
for(int x:g[u]){
if(x==p) continue;
dep[x]=dep[u]+1;
dfs(x,u);
}
}
int lca(int a,int b){
if(dep[a]<dep[b]) swap(a,b);
int d=dep[a]-dep[b];
while(d){
a=par[a][__lg(lowb(d))];
d-=lowb(d);
}
if(a==b){
return a;
}
for(int j=19;j>=0;j--){
if(par[a][j]!=par[b][j]){
a=par[a][j],b=par[b][j];
}
}
return par[a][0];
}
int get(int a,int b){
return dep[a]+dep[b]-2*dep[lca(a,b)];
}
int main(){
int n;
cin>>n;
REP(i,n){
int x;
cin>>x;
--x;
v.pb({x,i});
arr[i]=x;
}
uf.init(n);
REP(i,n-1){
int a,b;
cin>>a>>b;
--a,--b;
g[a].pb(b),g[b].pb(a);
}
dfs(0,-1);
REP1(j,19){
REP(i,n){
if(par[i][j-1]!=-1) par[i][j]=par[par[i][j-1]][j-1];
else par[i][j]=-1;
}
}
sort(ALL(v));
for(auto x:v){
for(int a:g[x.s]){
if(arr[a]>x.f) continue;
int p=uf.mx[uf.find(a)];
MXTO(dp[x.s],dp[p]+get(x.s,p));
uf.merge(a,x.s);
}
//cout<<dp[x.s]<<' ';
}
cout<<dp[v.back().s];
}
