#include <iostream>
#include <iomanip>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <cassert>
#include <ctime>
#include <chrono>
#include <cstdio>
#include <random>
#include <vector>
#include <string>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <deque>
#include <queue>
#include <bitset>
#include <list>
#include <fstream>
#include <functional>
#include <complex>
using namespace std;
mt19937_64 rnd(chrono::steady_clock::now().time_since_epoch().count());
short skip_cin = 0;
const long long INF = 1e18, MOD = 1e9 + 7, MOD2 = 998244353, LOG = 19;
const long double EPS = 1e-9, PI = acos(-1);
struct dsu
{
long long n;
vector<long long> p, rk, mx;
dsu(long long in, vector<long long>& val)
{
n = in;
p.resize(n);
iota(p.begin(), p.end(), 0);
rk.resize(n);
mx = val;
}
long long rt(long long v)
{
return (p[v] == v ? v : p[v] = rt(p[v]));
}
void unite(long long a, long long b)
{
a = rt(a);
b = rt(b);
if (a == b)
{
return;
}
if (rk[a] < rk[b])
{
swap(a, b);
}
mx[a] = max(mx[a], mx[b]);
p[b] = a;
rk[a] += (rk[a] == rk[b]);
}
};
long long n;
vector<long long> g[200000];
vector<long long> val, pos;
vector<long long> binup[200000];
vector<long long> h;
void build_binup(long long v, long long p)
{
h[v] = (p == -1 ? 0 : h[p] + 1);
binup[v][0] = (p == -1 ? v : p);
for (long long i = 1; i < LOG; i++)
{
binup[v][i] = binup[binup[v][i - 1]][i - 1];
}
for (auto& i : g[v])
{
if (i == p)
{
continue;
}
build_binup(i, v);
}
}
long long get_la(long long v, long long x)
{
for (long long i = LOG - 1; i > -1; i--)
{
if (h[v] - h[binup[v][i]] <= x)
{
x -= h[v] - h[binup[v][i]];
v = binup[v][i];
}
}
return v;
}
long long get_lca(long long a, long long b)
{
if (h[a] < h[b])
{
swap(a, b);
}
a = get_la(a, h[a] - h[b]);
if (a == b)
{
return a;
}
for (long long i = LOG - 1; i > -1; i--)
{
if (binup[a][i] != binup[b][i])
{
a = binup[a][i];
b = binup[b][i];
}
}
return binup[a][0];
}
long long dist(long long a, long long b)
{
long long c = get_lca(a, b);
return h[a] + h[b] - h[c] * 2;
}
vector<pair<long long, long long>> tr[200000];
vector<long long> dp;
void calc_dp(long long v)
{
dp[v] = 0;
for (auto& i : tr[v])
{
calc_dp(i.first);
dp[v] = max(dp[v], dp[i.first] + i.second);
}
}
void solve()
{
cin >> n;
val.resize(n);
pos.resize(n);
h.resize(n);
for (long long i = 0; i < n; i++)
{
cin >> val[i];
val[i]--;
pos[val[i]] = i;
}
for (long long i = 0; i < n - 1; i++)
{
long long a, b;
cin >> a >> b;
a--; b--;
g[a].push_back(b);
g[b].push_back(a);
}
for (long long i = 0; i < n; i++)
{
binup[i].resize(LOG);
}
build_binup(0, -1);
dsu kek(n, val);
for (long long ch = 0; ch < n; ch++)
{
long long v = pos[ch];
for (auto& i : g[v])
{
if (val[i] > val[v])
{
continue;
}
long long to = pos[kek.mx[kek.rt(i)]];
tr[v].push_back({ to, dist(v, to) });
kek.unite(v, i);
}
}
dp.resize(n);
calc_dp(pos[n - 1]);
cout << dp[pos[n - 1]] << "\n";
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
srand(time(NULL));
int tst = 1;
//cin >> tst;
while (tst--)
{
solve();
}
return 0;
}
/*
<3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3
⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⠤⠖⠚⢉⣩⣭⡭⠛⠓⠲⠦⣄⡀⠀⠀⠀⠀⠀⠀⠀
⠀⠀⠀⠀⠀⠀⢀⡴⠋⠁⠀⠀⠊⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠳⢦⡀⠀⠀⠀⠀
⠀⠀⠀⠀⢀⡴⠃⢀⡴⢳⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⣆⠀⠀⠀
⠀⠀⠀⠀⡾⠁⣠⠋⠀⠈⢧⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢧⠀⠀
⠀⠀⠀⣸⠁⢰⠃⠀⠀⠀⠈⢣⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣇⠀
⠀⠀⠀⡇⠀⡾⡀⠀⠀⠀⠀⣀⣹⣆⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢹⠀
⠀⠀⢸⠃⢀⣇⡈⠀⠀⠀⠀⠀⠀⢀⡑⢄⡀⢀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⡇
⠀⠀⢸⠀⢻⡟⡻⢶⡆⠀⠀⠀⠀⡼⠟⡳⢿⣦⡑⢄⠀⠀⠀⠀⠀⠀⠀⠀⢸⡇
⠀⠀⣸⠀⢸⠃⡇⢀⠇⠀⠀⠀⠀⠀⡼⠀⠀⠈⣿⡗⠂⠀⠀⠀⠀⠀⠀⠀⢸⠁
⠀⠀⡏⠀⣼⠀⢳⠊⠀⠀⠀⠀⠀⠀⠱⣀⣀⠔⣸⠁⠀⠀⠀⠀⠀⠀⠀⢠⡟⠀
⠀⠀⡇⢀⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠠⠀⡇⠀⠀⠀⠀⠀⠀⠀⠀⢸⠃⠀
⠀⢸⠃⠘⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⠁⠀⠀⢀⠀⠀⠀⠀⠀⣾⠀⠀
⠀⣸⠀⠀⠹⡄⠀⠀⠈⠁⠀⠀⠀⠀⠀⠀⠀⡞⠀⠀⠀⠸⠀⠀⠀⠀⠀⡇⠀⠀
⠀⡏⠀⠀⠀⠙⣆⠀⠀⠀⠀⠀⠀⠀⢀⣠⢶⡇⠀⠀⢰⡀⠀⠀⠀⠀⠀⡇⠀⠀
⢰⠇⡄⠀⠀⠀⡿⢣⣀⣀⣀⡤⠴⡞⠉⠀⢸⠀⠀⠀⣿⡇⠀⠀⠀⠀⠀⣧⠀⠀
⣸⠀⡇⠀⠀⠀⠀⠀⠀⠉⠀⠀⠀⢹⠀⠀⢸⠀⠀⢀⣿⠇⠀⠀⠀⠁⠀⢸⠀⠀
⣿⠀⡇⠀⠀⠀⠀⠀⢀⡤⠤⠶⠶⠾⠤⠄⢸⠀⡀⠸⣿⣀⠀⠀⠀⠀⠀⠈⣇⠀
⡇⠀⡇⠀⠀⡀⠀⡴⠋⠀⠀⠀⠀⠀⠀⠀⠸⡌⣵⡀⢳⡇⠀⠀⠀⠀⠀⠀⢹⡀
⡇⠀⠇⠀⠀⡇⡸⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⠮⢧⣀⣻⢂⠀⠀⠀⠀⠀⠀⢧
⣇⠀⢠⠀⠀⢳⠇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⡎⣆⠀⠀⠀⠀⠀⠘
⢻⠀⠈⠰⠀⢸⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠰⠘⢮⣧⡀⠀⠀⠀⠀
⠸⡆⠀⠀⠇⣾⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⠆⠀⠀⠀⠀⠀⠀⠀⠙⠳⣄⡀⢢⡀
<3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3 <3
*/
