#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
double cur = rngesus(0, MASK(60) - 1);
cur /= MASK(60) - 1;
return l + cur * (r - l);
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
struct DSU{
int n;
vector<int> parent, sz;
vector<pair<int, int>> dp;
DSU(int _n){
n = _n;
parent.resize(n+1); sz.resize(n+1, 1);
dp.resize(n+1);
for(int i = 1; i<=n; ++i) {
parent[i] = i;
dp[i] = {i, 0};
}
}
int find_set(int u){return (u == parent[u]) ? u : (parent[u] = find_set(parent[u]));}
bool same_set(int u, int v){return find_set(u) == find_set(v);}
bool join_set(int u, int v){
u = find_set(u), v = find_set(v);
if (u != v){
if (sz[u] < sz[v]) swap(u, v);
parent[v] = u;
sz[u] += sz[v];
dp[u] = dp[v];
return true;
}
return false;
}
int get_size(int u){return sz[find_set(u)];}
pair<int, int> get_dp(int u){return dp[find_set(u)];}
void set_dp(int u, pair<int, int> v){dp[find_set(u)] = v;}
};
const int N = 2e5 + 69, LOG_N = 18;
int n;
int a[N], p[N];
vector<int> graph[N];
int h[N], parent[N][LOG_N];
void dfs(int u, int p){
h[u] = h[p] + 1;
for(int j = 1; MASK(j) < h[u]; ++j)
parent[u][j] = parent[parent[u][j-1]][j-1];
for(int v: graph[u]) if (v != p){
parent[v][0] = u;
dfs(v, u);
}
}
int LCA(int u, int v){
if (h[u] < h[v]) swap(u, v);
int diff = h[u] - h[v];
for(int j = 0; j < LOG_N; ++j) if (GETBIT(diff, j))
u = parent[u][j];
if (u == v) return u;
for(int j = LOG_N - 1; j >= 0; --j) if (parent[u][j] != parent[v][j]){
u = parent[u][j];
v = parent[v][j];
}
return parent[u][0];
}
int path_length(int u, int v){
return h[u] + h[v] - 2*h[LCA(u, v)];
}
ll solve(){
cin >> n;
for(int i = 1; i <= n; ++i) cin >> a[i];
for(int i = 1; i <= n; ++i) p[a[i]] = i;
for(int i = 1; i < n; ++i){
int u, v; cin >> u >> v;
graph[u].push_back(v);
graph[v].push_back(u);
}
dfs(1, 0);
DSU mst(n);
vector<int> dp(n+1);
for(int i = 1; i <= n; ++i){
int u = p[i];
for(int v: graph[u]) if (a[v] < a[u]){
pair<int, int> cur = mst.get_dp(v);
maximize(dp[i], cur.second + path_length(cur.first, u));
mst.join_set(u, v);
}
mst.set_dp(u, make_pair(u, dp[i]));
}
return dp.back();
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
clock_t start = clock();
cout << solve() << "\n";
cerr << "Time elapsed: " << clock() - start << "ms!\n";
return 0;
}
