/* -*- coding: utf-8 -*-
 *
 * 3660.cc:  No.3660 LIS on Tree - yukicoder
 */

#include<cstdio>
#include<vector>
#include<algorithm>

using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

using ll = long long;
using vi = vector<int>;

/* global variables */

int ss[MAX_N];
vi nbrs[MAX_N];
int ps[MAX_N], cis[MAX_N];
ll xs[MAX_N], pxs[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", ss + i);
  for (int i = 1; i < n; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    u--, v--;
    nbrs[u].push_back(v);
    nbrs[v].push_back(u);
  }

  ps[0] = -1;
  for (int u = 0; u >= 0;) {
    auto &nbru = nbrs[u];
    int up = ps[u];

    if (cis[u] < (int)nbru.size()) {
      int v = nbru[cis[u]++];
      if (v != up) {
	ps[v] = u;
	u = v;
      }
    }
    else {
      xs[u] = max(xs[u], (ll)ss[u]);
      if (up >= 0 && ss[up] < ss[u])
	xs[up] = max(xs[up], xs[u] + ss[up]);
      u = up;
    }
  }
  //for (int i = 0; i < n; i++) printf(" %lld", xs[i]); putchar('\n');

  fill(cis, cis + n, 0);
  pxs[0] = ss[0];
  ll maxx = xs[0];
  for (int u = 0; u >= 0;) {
    auto &nbru = nbrs[u];
    int up = ps[u];

    if (cis[u] < (int)nbru.size()) {
      int v = nbru[cis[u]++];
      if (v != up) {
	pxs[v] = (ss[v] < ss[u]) ? pxs[u] + ss[v] : ss[v];
	maxx = max(maxx, max(xs[v], pxs[v]));
	u = v;
      }
    }
    else {
      u = up;
    }
  }

  printf("%lld\n", maxx);
  
  return 0;
}