q = int(input())
while q:
	q -= 1
	n = int(input())
	
	pc = 0
	m = n
	while m:
		pc += m & 1
		m >>= 1
	
	if pc == 1:
		print(-1)
		continue
	
	flag = 0
	
	ans = 0
	
	for id in range(30):
		if flag:
			if (n & (1 << id)):
				break
			else:
				ans += 1 << id

		else:
			if (n & (1 << id)):
				ans += 1 << id
				flag = 1
			else:
				pass
	
	print(ans)