from collections import defaultdict
import sys
sys.setrecursionlimit(10**6)

N = int(input())
S = list(map(int, input().split()))

adj = defaultdict(list)
degs = [0] * N
for _ in range(N-1):
    a, b = map(lambda x: int(x)-1, input().split())
    adj[a].append(b)
    adj[b].append(a)

    degs[a] += 1
    degs[b] += 1


def dfs(v):
    s = S[v]
    res = s
    for to in adj[v]:
        if s >= S[to]: continue
        res = max(res, s + dfs(to))

    return res


ans = 0
for i in range(N):
    skip = False
    for to in adj[i]:
        if S[to] > S[i]:
            b = True

    if not skip:
        ans = max(ans, dfs(i))

print(ans)