def shift(x):
	return x//2+pow(2,15)*(x%2)

def solve():
	N=int(input())
	A=list(map(int,input().split()))
	
	if N>=16:
		return (1<<16)-1
		
	X=1<<16
	D=[0]*X; D[0]=1
	
	for a in A:
		E=D.copy()
		D=[0]*X
		for _ in range(16):
			for x in range(X):
				D[x|a]|=E[x]
			a=shift(a)
	
	return max([i for i in range(X) if D[i]])

print(solve())