# https://yukicoder.me/problems/no/1219

from collections import deque

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


    def dfs(a_array, k):
        if len(a_array) == 0:
            return 0
        if k < 0:
            return 0

        count = [[], []]
        for a in a_array:
            if (1 << k) & a > 0:
                count[1].append(a)
            else:
                count[0].append(a)

        if len(count[0]) > 0 and len(count[1]) > 0:        
            answer = 1 << k
            ans0 = dfs(count[0], k - 1)
            ans1 = dfs(count[1], k - 1)
            answer += min(ans0, ans1)
        elif len(count[0]) > 0:
            answer = dfs(count[0], k - 1)
        elif len(count[1]) > 0:
            answer = dfs(count[1], k - 1)

        return answer

    max_a = max(A)
    k = 0
    while max_a > 0:
        k += 1
        max_a //= 2
    k += 1

    answer = dfs(A, k)
    print(answer)




if __name__ == "__main__":
    main()