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

    def insert(self, num, bit):
        if bit < 0:
            return
        b = (num >> bit) & 1
        if not self.children[b]:
            self.children[b] = TrieNode()
        self.children[b].insert(num, bit - 1)

def main():
    import sys
    input = sys.stdin.read().split()
    n = int(input[0])
    a = list(map(int, input[1:n+1]))

    max_bit = 30
    root = TrieNode()
    for num in a:
        root.insert(num, max_bit)

    def min_max_xor(node, bit):
        if bit < 0:
            return 0
        left = node.children[0]
        right = node.children[1]
        if not left and not right:
            return 0
        if not left or not right:
            child = left if left else right
            return min_max_xor(child, bit - 1)
        else:
            return (1 << bit) + min(min_max_xor(left, bit - 1), min_max_xor(right, bit - 1))

    print(min_max_xor(root, max_bit))

if __name__ == '__main__':
    main()