//#define _GLIBCXX_DEBUG #include <bits/stdc++.h> #define int long long using namespace std; const int MAXN = 2e5 + 1; const int MAXLOG = 21; struct cnm { vector <int> sz,pr,best_ans,mx,tmp; cnm(int n) { for (int i = 0;i < n;i++) { sz.push_back(1); pr.push_back(i); best_ans.push_back(0); mx.push_back(i); } } int get(int u) { if (pr[u] == u)return u; return pr[u] = get(pr[u]); } void merge(int a,int b,int newcost) { a = get(a); b = get(b); if (a == b) return; if (sz[a] < sz[b]) { swap(a,b); } pr[b] = a; sz[a] += sz[b]; if (tmp[mx[a]] < tmp[mx[b]]) { mx[a] = mx[b]; } best_ans[a] = max({best_ans[a],newcost,best_ans[b]}); } int get_mx(int u) { u = get(u); return mx[u]; } }; int binup[MAXN][MAXLOG]; int tin[MAXN]; int tout[MAXN]; int t = 0; void dfs(int u,int p,vector <vector <int>> &g) { tin[u] = t++; if (p == -1) { for (int i = 0;i < MAXLOG;i++) { binup[u][i] = u; } }else { for (int i = 1;i < MAXLOG;i++) { binup[u][i] = binup[binup[u][i-1]][i-1]; } } for (auto el : g[u]) { if (el == p)continue; binup[el][0] = u; dfs(el,u,g); } tout[u] = t++; } bool is_ans(int a,int b) { return tin[a] <= tin[b] && tout[a] >= tout[b]; } int len(int a,int b) { if (a == b)return 0; if (is_ans(a,b))swap(a,b); int ans = 0; for (int i = MAXLOG - 1;i >= 0;i--) { if (!is_ans(binup[a][i],b)) { ans += (1ll << i); a = binup[a][i]; } } a = binup[a][0]; ans++; if (a == b)return ans; swap(a,b); for (int i = MAXLOG - 1;i >= 0;i--) { if (!is_ans(binup[a][i],b)) { ans += (1ll << i); a = binup[a][i]; } } return ans + 1; } signed main() { ios_base::sync_with_stdio(false); cin.tie(NULL); int n; cin >> n; vector <int> vec(n); int ind = -1; for (int i = 0;i < n;i++) { cin >> vec[i]; vec[i]--; if (vec[i] == n-1) { ind = i; } } vector <vector <int>> g(n); for (int i = 1;i < n;i++) { int u,v; cin >> u >> v; u--; v--; g[u].push_back(v); g[v].push_back(u); } vector <int> obxod(n); for (int i = 0;i < n;i++) { obxod[vec[i]] = i; } dfs(0,-1,g); cnm cm(n); cm.tmp = vec; for (int i = 0;i < n;i++) { int u = obxod[i]; for (auto el : g[u]) { if (vec[el] > vec[u]) { continue; } int plus = len(u,cm.get_mx(el)); cm.merge(u,el,plus + cm.best_ans[cm.get(el)]); } } cout << cm.best_ans[cm.get(0)] << '\n'; }