# BIT DP を行う
# A[i] > 0 だから, 最大16個見ればok 
# dp[i][j] : i番目まで見てjが到達可能

n = int(input())
a = list(map(int,input().split()))
dp = [[0] * (1 << 16) for i in range(min(n, 16) + 1)]
dp[0][0] = 1

for i in range(min(n, 16)):
	for j in range(16):
		for k in range(1 << 16):
			if dp[i][k] == 1:
				dp[i+1][k|a[i]] = 1
		a[i] = (a[i] // 2) + (1 << 15) * (a[i] % 2)

r = 0
for i in range(1 << 16):
	if dp[min(n, 16)][i] == 1:
		r = i

print(r)