import sys
sys.setrecursionlimit(10 ** 9)

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

def dfs(array, i):
    if i<0:return 0
    zero=[]
    one=[]
    for a in array:
        if (a>>i)&1:
            one.append(a^(1<<i))
        else:
            zero.append(a)

    if not one:
        return dfs(array,i-1)
    elif not zero:
        return dfs(array,i-1)
    else:
        return (1<<i)+min(dfs(one,i-1),dfs(zero,i-1))

print(dfs(A,32))