import sys
input = sys.stdin.readline

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

E=[[] for i in range(N)]

for i in range(N-1):
    x,y=list(map(int,input().split()))
    x-=1
    y-=1

    E[x].append(y)
    E[y].append(x)

XA=[(A[i],i) for i in range(N)]
XA.sort()

S=A[:]

for s,ind in XA:
    now=S[ind]

    for to in E[ind]:
        if A[to]>A[ind]:
            S[to]=max(S[to],A[to]+S[ind])

print(max(S))