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

def f(n,s):
    if(n == -1):return min(list(s) + [0])
    zero,one = [],[]
    for i in s:
        if(i>>n & 1 == 0):
            zero.append(i)
        else:
            one.append(i)

    if(not zero):
        return f(n-1, [i ^ (1<<n) for i in one])
    elif(not one):
        return f(n-1, [i for i in zero])
    else:
        return max(f(n-1, [i for i in zero]), f(n-1, [i ^ (1<<n) for i in one])) + (1<<n)

print(f(30,A))