// #pragma GCC optimize("Ofast","unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define int long long
struct segtree {
vector<int> tree;
segtree():tree(524288){}
int get(int a,int b) {
a+=262144;b+=262144;
int ans = 0;
while(a<=b) {
if(a&1)ans=max(ans,tree[a++]);
if(b%2==0)ans=max(ans,tree[b--]);
a/=2;b/=2;
}
return ans;
}
void update(int k,int x) {
k+=262144;
tree[k]=x;
while(k/=2)tree[k]=max(tree[2*k],tree[2*k+1]);
}
};
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
vector<int> P(n+1);
segtree seg;
vector<int> lookup(n+1);
for(int i=1;i<=n;i++) {
cin>>P[i];
lookup[P[i]]=i;
seg.update(i,P[i]);
}
vector<vector<int>> adj(n+1);
for(int i=1;i<n;i++) {
int a,b;cin>>a>>b;
adj[a].emplace_back(b);
adj[b].emplace_back(a);
}
vector<int> DP(n+1);
for(int i=n;i;i--) {
int idx = lookup[i];
int r = idx-1;
for(int jump=(1<<17);jump;jump/=2) {
if(r+jump<=n and seg.get(idx,r+jump)==i)r+=jump;
}
r++;
if(r==n+1)r=idx;
int l = idx+1;
for(int jump=(1<<17);jump;jump/=2) {
if(l-jump>=1 and seg.get(l-jump,idx)==i)l-=jump;
}
l--;
if(l==0)l=idx;
DP[idx]=max(DP[r]+r-idx,DP[l]+idx-l);
}
cout << *max_element(DP.begin(),DP.end()) << '\n';
}
