n = int(input())
a = list(map(int, input().split()))
ans = [0] * n
edge = [list(map(int, input().split()))for _ in range(n - 1)]
edge.sort(key = lambda x: min(a[x[0] - 1], a[x[1] - 1]))
for x, y in edge:
    if a[x - 1] == a[y - 1]:
        continue
    if a[x - 1] < a[y - 1]:
        x, y = y, x
    ans[x - 1] = max(ans[x - 1], a[y - 1] + ans[y - 1])
print(max(ans[i] + a[i] for i in range(n)))