import sys
input = sys.stdin.readline

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

ANS=0

for i in range(31,-1,-1):
    if i%2==0:
        B=[]
        for a in A:
            if a & (1<<i) != 0:
                B.append(a)

        X=0

        for b in B:
            X|=b

        if X!=0 and (X & ANS) ==ANS:
            ANS|=(1<<i)
            A=B
        

    else:
        flag=0
        for a in A:
            if a& (1<<i) != 0:
                flag=1

        if flag==1:
            ANS|=(1<<i)

print(ANS)