#include<bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define int long long
#define vi vector<int>
#define vvi vector<vector<int>>
#define pii pair<int, int>
#define vpii vector<pair<int, int>>
#define vc vector<char>
#define vb vector<bool>
#define mii map<int,int>
#define f0r(i,n) for(int i=0;i<n;i++)
#define FOR(i,k,n) for(int i=k;i<n;i++)
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define in(a) int a; cin>>a
#define in2(a,b) int a,b; cin>>a>>b
#define in3(a,b,c) int a,b,c; cin>>a>>b>>c
#define in4(a,b,c,d) int a,b,c,d; cin>>a>>b>>c>>d
#define vin(v,n); vi v(n); f0r(i,n){cin>>v[i];}
#define out(a) cout<<a<<'\n'
#define out2(a,b) cout<<a<<' '<<b<<'\n'
#define out3(a,b,c) cout<<a<<' '<<b<<' '<<c<<'\n'
#define out4(a,b,c,d) cout<<a<<' '<<b<<' '<<c<<' '<<d<<'\n'
#define pout(a) cout<<a.first<<' '<<a.second<<'\n'
#define vout(v) for(auto u : v){cout<<u<<' ';} cout<<'\n'
#define dout(a) cout<<a<<' '<<#a<<'\n'
#define dout2(a,b) cout<<a<<' '<<#a<<' '<<b<<' '<<#b<<'\n'
#define yn(x); if(x){cout<<"YES"<<'\n';}else{cout<<"NO"<<'\n';}
const int leg = 1e9 + 7;
const int mod = 998244353;
using namespace std;
struct maxsegtree{
vpii tree;
int n;
void update(int k, int x){
k += n;
tree[k] = mp(x,k-n);
for(k/=2;k>=1;k/=2){
tree[k] = max(tree[k*2], tree[k*2+1]);
}
}
int quer(int l, int r){
pii ret = {-1,-1};
l+=n; r+=n;
while(l<=r){
if(l % 2 == 1)ret = max(ret, tree[l++]);
if(r % 2 == 0)ret = max(ret, tree[r--]);
l/=2; r/=2;
}
return ret.second;
}
maxsegtree(vi &a){
n = a.size();
tree.resize(2*n+5);
f0r(i,n)update(i, a[i]);
}
};
struct DSU{
int n;
vi par;
vi sz;
vpii rng;
DSU(int x){
n = x;
par.resize(x);
sz.resize(x);
rng.resize(x);
f0r(i,x){
par[i] = i;
sz[i] = 1;
rng[i] = mp(i,i);
}
}
int find(int x){
while(x != par[x])x = par[x];
return x;
}
pii r(int x){
x = find(x);
return rng[x];
}
void unite(int a, int b){
a = find(a);
b = find(b);
if(a == b)return;
if(sz[a] < sz[b])swap(a,b);
sz[a] += sz[b];
par[b] = a;
rng[a] = mp(min(rng[a].first, rng[b].first), max(rng[a].second,rng[b].second));
}
};
signed main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
//ifstream cin(".in");
//ofstream cout(".out");
in(n);
vin(v,n);
vvi adj(n);
f0r(i,n-1){
in2(a,b);
a--; b--;
adj[a].pb(b);
adj[b].pb(a);
}
f0r(i,n){
v[i]--;
}
maxsegtree t = maxsegtree(v);
DSU d = DSU(n);
vi numtonode(n);
f0r(i,n){
numtonode[v[i]] = i;
}
vector<vpii> nxt(n);
f0r(i,n){
int g = numtonode[i];
if(numtonode[i] != 0 && v[numtonode[i] - 1] < i){
d.unite(g-1, g);
}
if(numtonode[i] != n-1 && v[numtonode[i] + 1] < i){
d.unite(g, g+1);
}
pii rng = d.r(numtonode[i]);
if(numtonode[i] != rng.first){
int mxd = t.quer(rng.first, numtonode[i]-1);
nxt[i].pb(mp(v[mxd], i - mxd));
}
if(numtonode[i] != rng.second){
int mxd = t.quer(numtonode[i] + 1, rng.second);
nxt[i].pb(mp(v[mxd], mxd - i));
}
}
vi dp(n);
dp[n-1] = 0;
for(int i = n-1; i>=0; i--){
// dout(i);
for(pii x : nxt[i]){
// pout(x);
dp[x.first] = max(dp[x.first], dp[i] + x.second);
}
// cout<<'\n';
}
out(*max_element(all(dp)));
}
