#include <bits/stdc++.h>
#define int long long
const int LOGN = 20;
struct DSU
{
int n;
std::vector<int> p;
DSU(int n) : n(n)
{
p.resize(n);
std::iota(p.begin(), p.end(), 0);
}
int pred(int a)
{
if (a == p[a])
{
return a;
}
p[a] = pred(p[a]);
return p[a];
}
void mer(int a, int b)
{
a = pred(a), b = pred(b);
if (a == b)
return;
p[a] = b;
}
};
const int MAXN = 2 * 1e5 + 1;
int up[MAXN][LOGN];
int h[MAXN];
void dfs(int v, std::vector<std::vector<int>> &g, int height = 0, int pred = -1)
{
h[v] = height;
for (int i = 1; i < LOGN; i++)
{
up[v][i] = up[up[v][i - 1]][i - 1];
}
for (int u : g[v])
{
if (u != pred)
{
up[u][0] = v;
dfs(u, g, height + 1, v);
}
}
}
int Dist(int a, int b)
{
int dist1 = h[a];
int dist2 = h[b];
if (h[a] > h[b])
{
std::swap(a, b);
}
for (int i = LOGN - 1; i >= 0; i--)
{
if ((h[b] - h[a]) >= (1 << i))
{
b = up[b][i];
}
}
if (a == b)
{
return dist1 + dist2 - 2 * h[a];
}
for (int i = LOGN - 1; i >= 0; i--)
{
if (up[a][i] != up[b][i])
{
a = up[a][i];
b = up[b][i];
}
}
a = up[a][0];
return dist1 + dist2 - 2 * h[a];
}
signed main()
{
std::ios::sync_with_stdio(false);
std::cin.tie(0);
int n;
std::cin >> n;
std::vector<int> p(n);
for (int i = 0; i < n; i++)
{
std::cin >> p[i];
}
std::vector<int> help(n);
for (int i = 0; i < n; i++)
{
p[i]--;
help[p[i]] = i;
}
std::vector<std::vector<int>> g(n);
for (int i = 0; i < n - 1; i++)
{
int a, b;
std::cin >> a >> b;
a--, b--;
g[a].push_back(b);
g[b].push_back(a);
}
up[0][0] = 0;
dfs(0, g);
DSU t(n);
std::vector<int> dp(n, -1);
for (int v : help)
{
dp[v] = 0;
for (int u : g[v])
{
if (dp[u] == -1)
{
continue;
}
u = t.pred(u);
dp[v] = std::max(dp[v], dp[u] + Dist(v, u));
// std::cout << v << ' ' << u << ' ' << Dist(v, u) << std::endl;
t.mer(u, v);
}
}
std::cout << dp[help.back()];
}
