class TrieNode:
    def __init__(self):
        self.next = [None, None]

class Trie:
    def __init__(self):
        self.root = TrieNode()

    def append(self, s: str):
        cur = self.root
        for ch in s:
            idx = 0 if ch == '0' else 1
            if cur.next[idx] is None:
                new_node = TrieNode()
                cur.next[idx] = new_node

            cur = cur.next[idx]

    def getRoot(self) -> TrieNode:
        return self.root


def dfs(dep, max_dep, node1: TrieNode, node2: TrieNode) ->int:
    if dep == max_dep:
        return 0

    max_val = 0
    flag = False
    if node1.next[1] is not None and node2.next[0] is not None:
        flag = True
        max_val = max(max_val, dfs(dep+1, max_dep, node1.next[1], node2.next[0]))

    if node1.next[0] is not None and node2.next[1] is not None:
        flag = True
        max_val = max(max_val, dfs(dep+1, max_dep, node1.next[0], node2.next[1]))

    if flag:
        ans = max_val | (1 << (max_dep-1-dep))
        return ans

    if node1.next[0] is not None:
        return dfs(dep+1, max_dep, node1.next[0], node2.next[0])
    else:
        return dfs(dep+1, max_dep, node1.next[1], node2.next[1])

n = int(input())
arr = list( map(int, input().split()) )
trie = Trie()
max_len = 0
ss = []
for val in arr:
    s = '{:b}'.format(val)
    max_len = max(max_len, len(s))
    ss.append(s)
for s in ss:
    s = '0' * (max_len - len(s)) + s
    trie.append(s)

print(dfs(0, max_len, trie.root, trie.root))