import math
from collections import deque
from bisect import bisect_left, bisect_right
from typing import Generic, Iterable, Iterator, TypeVar
from sys import setrecursionlimit
T = TypeVar('T')


class SortedSet(Generic[T]):
    BUCKET_RATIO = 16
    SPLIT_RATIO = 24

    def __init__(self, a: Iterable[T] = []) -> None:
        "Make a new SortedSet from iterable. / O(N) if sorted and unique / O(N log N)"
        a = list(a)
        n = len(a)
        if any(a[i] > a[i + 1] for i in range(n - 1)):
            a.sort()
        if any(a[i] >= a[i + 1] for i in range(n - 1)):
            a, b = [], a
            for x in b:
                if not a or a[-1] != x:
                    a.append(x)
        n = self.size = len(a)
        num_bucket = int(math.ceil(math.sqrt(n / self.BUCKET_RATIO)))
        self.a = [a[n * i // num_bucket: n *
                    (i + 1) // num_bucket] for i in range(num_bucket)]

    def __iter__(self) -> Iterator[T]:
        for i in self.a:
            for j in i:
                yield j

    def __reversed__(self) -> Iterator[T]:
        for i in reversed(self.a):
            for j in reversed(i):
                yield j

    def __eq__(self, other) -> bool:
        return list(self) == list(other)

    def __len__(self) -> int:
        return self.size

    def __repr__(self) -> str:
        return "SortedSet" + str(self.a)

    def __str__(self) -> str:
        s = str(list(self))
        return "{" + s[1: len(s) - 1] + "}"

    def _position(self, x: T) -> tuple[list[T], int, int]:
        "return the bucket, index of the bucket and position in which x should be. self must not be empty."
        for i, a in enumerate(self.a):
            if x <= a[-1]:
                break
        return (a, i, bisect_left(a, x))

    def __contains__(self, x: T) -> bool:
        if self.size == 0:
            return False
        a, _, i = self._position(x)
        return i != len(a) and a[i] == x

    def add(self, x: T) -> bool:
        "Add an element and return True if added. / O(√N)"
        if self.size == 0:
            self.a = [[x]]
            self.size = 1
            return True
        a, b, i = self._position(x)
        if i != len(a) and a[i] == x:
            return False
        a.insert(i, x)
        self.size += 1
        if len(a) > len(self.a) * self.SPLIT_RATIO:
            mid = len(a) >> 1
            self.a[b:b+1] = [a[:mid], a[mid:]]
        return True

    def _pop(self, a: list[T], b: int, i: int) -> T:
        ans = a.pop(i)
        self.size -= 1
        if not a:
            del self.a[b]
        return ans

    def discard(self, x: T) -> bool:
        "Remove an element and return True if removed. / O(√N)"
        if self.size == 0:
            return False
        a, b, i = self._position(x)
        if i == len(a) or a[i] != x:
            return False
        self._pop(a, b, i)
        return True

    def lt(self, x: T) -> T | None:
        "Find the largest element < x, or None if it doesn't exist."
        for a in reversed(self.a):
            if a[0] < x:
                return a[bisect_left(a, x) - 1]

    def le(self, x: T) -> T | None:
        "Find the largest element <= x, or None if it doesn't exist."
        for a in reversed(self.a):
            if a[0] <= x:
                return a[bisect_right(a, x) - 1]

    def gt(self, x: T) -> T | None:
        "Find the smallest element > x, or None if it doesn't exist."
        for a in self.a:
            if a[-1] > x:
                return a[bisect_right(a, x)]

    def ge(self, x: T) -> T | None:
        "Find the smallest element >= x, or None if it doesn't exist."
        for a in self.a:
            if a[-1] >= x:
                return a[bisect_left(a, x)]

    def __getitem__(self, i: int) -> T:
        "Return the i-th element."
        if i < 0:
            for a in reversed(self.a):
                i += len(a)
                if i >= 0:
                    return a[i]
        else:
            for a in self.a:
                if i < len(a):
                    return a[i]
                i -= len(a)
        raise IndexError

    def pop(self, i: int = -1) -> T:
        "Pop and return the i-th element."
        if i < 0:
            for b, a in enumerate(reversed(self.a)):
                i += len(a)
                if i >= 0:
                    return self._pop(a, ~b, i)
        else:
            for b, a in enumerate(self.a):
                if i < len(a):
                    return self._pop(a, b, i)
                i -= len(a)
        raise IndexError

    def index(self, x: T) -> int:
        "Count the number of elements < x."
        ans = 0
        for a in self.a:
            if a[-1] >= x:
                return ans + bisect_left(a, x)
            ans += len(a)
        return ans

    def index_right(self, x: T) -> int:
        "Count the number of elements <= x."
        ans = 0
        for a in self.a:
            if a[-1] > x:
                return ans + bisect_right(a, x)
            ans += len(a)
        return ans


def main():
    setrecursionlimit(1000000)
    N = int(input())
    W = list(map(int, input().split()))
    G = [[] for _ in range(N)]
    for _ in range(N - 1):
        U, V = map(int, input().split())
        U -= 1
        V -= 1
        G[U].append(V)
        G[V].append(U)

    subtree = W[:]
    par = [-1] * N

    def dfs_subtree(v, p):
        par[v] = p
        for u in G[v]:
            if u != p:
                subtree[v] += dfs_subtree(u, v)
        return subtree[v]

    dfs_subtree(0, -1)

    gr = 0
    # 重心探索
    while True:
        br = True
        for u in G[gr]:
            if u == par[gr]:
                continue
            if subtree[u] * 2 >= subtree[0]:
                gr = u
                br = False
                break
        if br:
            break

    # 重心を根として部分木サイズを再計算
    subtree = W[:]
    dfs_subtree(gr, -1)

    ans = subtree[gr]
    cut1 = SortedSet[int]()

    for s in G[gr]:
        bfs = deque([s])
        d = []
        while bfs:
            v = bfs.popleft()
            d.append(subtree[v])
            for u in G[v]:
                if u != par[v]:
                    bfs.append(u)

        # 異なる部分木を切る場合 S1 - S2(G) - S3
        for w in d:
            mid = (subtree[gr] - w + 1) // 2
            it = cut1.ge(mid)
            if it:
                ans = min(
                    ans, max(it, w, subtree[gr] - w - it) - min(it, w, subtree[gr] - w - it))
            it = cut1.le(mid)
            if it:
                ans = min(
                    ans, max(it, w, subtree[gr] - w - it) - min(it, w, subtree[gr] - w - it))

        # 同じ部分木を2つに分ける場合 S1(G) - S2 - S3
        for w in d:
            ans = min(ans, max(subtree[gr] - subtree[s], w, subtree[s] - w)
                      - min(subtree[gr] - subtree[s], w, subtree[s] - w))

        for w in d:
            cut1.add(w)

    print(ans)


if __name__ == "__main__":
    main()