N=int(input())
A=list(map(int, input().split()))
A.sort()
M=A[-1]
L=M.bit_length()
for i in range(L)[::-1]:
    if (M>>i)&1==0:
        continue
    B=[]
    cnt=0
    for a in A:
        if (a>>i)&1:
            B.append(a)
        else:
            cnt+=1
    if cnt==0:
        A=[]
        M^=(1<<i)
        for b in B:
            A.append(b^(1<<i))
    else:
        A=B
print(M)