#include <iostream> #include <vector> #include <math.h> using namespace std; constexpr int N = 2e5 + 5; constexpr int logN = static_cast<int>(log2(N)); int n; int at[N]; vector<int> tree[N]; int timer; int tin[N], tout[N]; int depth[N]; int up[N][logN + 1]; void dfs(int u, int p) { up[u][0] = p; for (int i = 0; i < logN; i++) { up[u][i + 1] = up[up[u][i]][i]; } tin[u] = ++timer; for (int v : tree[u]) { if (v == p) continue; depth[v] = depth[u] + 1; dfs(v, u); } tout[u] = timer; } inline bool is_ancestor(int a, int d) { return tin[a] <= tin[d] && tin[d] <= tout[a]; } int lca(int u, int v) { if (is_ancestor(u, v)) return u; if (is_ancestor(v, u)) return v; for (int i = logN; i >= 0; i--) { if (is_ancestor(up[u][i], v)) continue; u = up[u][i]; } return up[u][0]; } inline int dist(int u, int v) { return depth[u] + depth[v] - 2 * depth[lca(u, v)]; } int dp[N]; int headquarter[N]; int parent[N]; int renk[N]; inline bool is_set(int u) { return parent[u] != 0; } inline void make_set(int u) { parent[u] = u; } int find_set(int u) { if (parent[u] == u) return u; return parent[u] = find_set(parent[u]); } inline void union_sets(int u, int v) { u = find_set(u); v = find_set(v); if (renk[u] >= renk[v]) { if (renk[u] == renk[v]) renk[v]++; parent[v] = u; } else { parent[u] = v; } } signed main() { ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); // freopen("input.txt", "r", stdin); cin >> n; for (int u = 1; u <= n; u++) { int h; cin >> h; at[h] = u; } for (int e = 1; e < n; e++) { int u, v; cin >> u >> v; tree[u].push_back(v); tree[v].push_back(u); } dfs(1, 1); for (int h = 1; h <= n; h++) { int u = at[h]; int maxd = 0; make_set(u); for (int v : tree[u]) { if (!is_set(v)) continue; maxd = max(maxd, dp[find_set(v)] + dist(u, headquarter[find_set(v)])); union_sets(u, v); } dp[find_set(u)] = maxd; headquarter[find_set(u)] = u; } cout << dp[at[n]]; return 0; }