#include<bits/stdc++.h>
#define IOS ios_base::sync_with_stdio(false);cin.tie();cout.tie();
#define all(x) x.begin(), x.end()
#define int long long
#define pq priority_queue
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define pb push_back
#define pp pop_back
#define F first
#define S second
using namespace std;
int n;
vector<int> N;
vector<int> v;
vector<int> P;
void build(int id, int L, int R) {
if (L + 1 == R) {N[id] = v[L]; return ;}
int M = (L + R) / 2, x = 2 * id, y = x + 1;
build(x, L, M);
build(y, M, R);
N[id] = max(N[x], N[y]);
}
int query(int id, int L, int R, int l, int r) {
if (L >= r || l >= R) return 0;
if (L >= l && r >= R) return N[id];
int M = (L + R) / 2, x = 2 * id, y = x + 1;
int sl = query(x, L, M, l, r);
int sr = query(y, M, R, l, r);
return max(sl, sr);
}
int calc(int M, int L, int R) {
if (M == 0 || L + 1 == R) return 0;
if (P[M] == L) {
int r = query(1, 0, n, P[M] + 1, R);
return calc(r, P[M] + 1, R) + P[r] - P[M];
}
if (P[M] + 1 == R) {
int l = query(1, 0, n, L, P[M]);
return calc(l, L, P[M]) + P[M] - P[l];
}
int l = query(1, 0, n, L, P[M]);
int r = query(1, 0, n, P[M] + 1, R);
return max(calc(l, L, P[M]) + P[M] - P[l], calc(r, P[M] + 1, R) + P[r] - P[M]);
}
void solve() {
cin >> n;
v = vector<int>(n);
P = vector<int>(n);
for (int i = 0; i < n; i++) {cin >> v[i]; v[i]--; P[v[i]] = i;}
for (int i = 1, a, b; i < n; i++) cin >> a >> b;
N = vector<int>(4*n, 0);
build(1, 0, n);
cout << calc(n - 1, 0, n) << '\n';
}
signed main() {IOS solve(); return 0;}
