use std::collections::VecDeque;

use proconio::{input, marker::Usize1};

fn solve() -> u64 {
  input! {
    n: usize,
    s: [u64; n],
    ab: [(Usize1, Usize1); n - 1],
  }
  let mut g = vec![vec![]; n];
  let mut d = vec![0; n];
  for &(ai, bi) in ab.iter() {
    if s[ai] > s[bi] {
      g[bi].push(ai);
      d[ai] += 1;
    } else if s[ai] < s[bi] {
      g[ai].push(bi);
      d[bi] += 1;
    }
  }
  let mut ls = vec![0; n];
  let mut q = VecDeque::new();
  d.iter().enumerate().for_each(|(i, &di)| if di == 0 {
    q.push_back(i);
    ls[i] = s[i];
  });
  while let Some(cur) = q.pop_front() {
    for &nxt in g[cur].iter() {
      ls[nxt] = ls[nxt].max(ls[cur] + s[nxt]);
      d[nxt] -= 1;
      if d[nxt] == 0 {
        q.push_back(nxt);
      }
    }
  }
  *ls.iter().max().unwrap()
}

fn main() {
  let ans = solve();
  println!("{}", ans);
}