from collections import deque

N = int(input())
S = list(map(int, input().split()))
G = [[] for _ in range(N)]
cnt = [0]*N
for _ in range(N-1):
    u, v = map(int, input().split())
    u, v = u-1, v-1
    if S[u] < S[v]:
        G[u].append(v)
        cnt[v] += 1
    elif S[v] < S[u]:
        G[v].append(u)
        cnt[u] += 1

que = deque()
for i in range(N):
    if cnt[i] == 0:
        que.append(i)

order = []
while que:
    n = que.popleft()
    order.append(n)
    for v in G[n]:
        cnt[v] -= 1
        if cnt[v] == 0:
            que.append(v)

dp = S[:]
for n in order:
    for v in G[n]:
        dp[v] = max(dp[v], dp[n]+S[v])

print(max(dp))