#include <bits/stdc++.h>
using namespace std;
template<typename T>
bool maximize(T& a, const T& b){
if(a < b){
return a = b, true;
} return false;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
freopen("task.inp", "r", stdin);
freopen("task.out", "w", stdout);
#endif // LOCAL
struct DisjointSet{
vector<int> lab, mx;
DisjointSet(int n) : lab(n, -1), mx(n) {
for(int i = 0; i < n; ++i) mx[i] = i;
}
int root(int u){
return lab[u] < 0 ? u : (lab[u] = root(lab[u]));
}
bool unite(int u, int v){
u = root(u);
v = root(v);
if(u == v) return false;
if(lab[u] > lab[v]) swap(u, v);
lab[u] += lab[v];
lab[v] = u;
maximize(mx[u], mx[v]);
return true;
}
int maxLabel(int u){
return mx[root(u)];
}
};
int N;
cin >> N;
vector<int> P(N);
for(int i = 0; i < N; ++i) cin >> P[i], --P[i];
vector<vector<int>> adj(N);
for(int i = 1; i < N; ++i){
int u, v;
cin >> u >> v;
--u, --v;
u = P[u];
v = P[v];
adj[u].push_back(v);
adj[v].push_back(u);
}
int timerdfs = 0;
vector<int> depth(N);
vector<int> tin(N), tout(N);
vector<vector<int>> lift(32 - __builtin_clz(N), vector<int>(N));
function<void(int, int)> dfs = [&](int u, int pre){
tin[u] = ++timerdfs;
for(int v : adj[u]) if(v != pre){
depth[v] = depth[u] + 1;
lift[0][v] = u;
for(int i = 1; (1 << i) <= depth[v]; ++i)
lift[i][v] = lift[i - 1][lift[i - 1][v]];
dfs(v, u);
}
tout[u] = timerdfs;
};
auto inside = [&](int u, int v) -> bool{
return tin[u] <= tin[v] && tout[v] <= tout[u];
};
auto getLCA = [&](int u, int v) -> int{
if(inside(u, v)) return u;
if(inside(v, u)) return v;
for(int i = 31 - __builtin_clz(depth[u]); i >= 0; --i){
if(depth[u] >= (1 << i) && !inside(lift[i][u], v)){
u = lift[i][u];
}
}
return lift[0][u];
};
auto distance = [&](int u, int v) -> int{
return depth[u] + depth[v] - 2 * depth[getLCA(u, v)];
};
dfs(N - 1, -1);
DisjointSet dsu(N);
vector<int> dp(N, 0);
for(int i = 1; i < N; ++i){
for(int j : adj[i]) if(j < i){
int mx = dsu.maxLabel(j);
maximize(dp[i], dp[mx] + distance(mx, i));
dsu.unite(i, j);
}
}
cout << dp[N - 1] << '\n';
return 0;
}
