import pypyjit
pypyjit.set_param("max_unroll_recursion=-1")
import sys
sys.setrecursionlimit(2*10**5+100)

from functools import cache
N = int(input())
S = list(map(int,input().split()))
edge = [[] for _ in range(N)]
for _ in range(N-1):
    a,b = list(map(int,input().split()))
    a -= 1;b -= 1
    edge[a].append(b)
    edge[b].append(a)

@cache
def dfs(n):
    ret = S[n]
    for i in edge[n]:
        if(S[n] >= S[i]):continue
        ret = max(ret, dfs(i) + S[n])

    return ret

ans = 0
for i in range(N):
    ans = max(ans,dfs(i))
print(ans)