In CODE FESTIVAL XXXX, there are N+1 participants from all over the world, including Takahashi.

Takahashi checked and found that the time gap (defined below) between the local times in his city and the i-th person's city was D_i hours. The time gap between two cities is defined as follows. For two cities A and B, if the local time in city B is d o'clock at the moment when the local time in city A is 0 o'clock, then the time gap between these two cities is defined to be min(d,24-d) hours. Here, we are using 24-hour notation. That is, the local time in the i-th person's city is either d o'clock or 24-d o'clock at the moment when the local time in Takahashi's city is 0 o'clock, for example.

Then, for each pair of two people chosen from the N+1 people, he wrote out the time gap between their cities. Let the smallest time gap among them be s hours.

Find the maximum possible value of s.

Constraints

* 1 \leq N \leq 50
* 0 \leq D_i \leq 12
* All input values are integers.

Input

Input is given from Standard Input in the following format:


N
D_1 D_2 ... D_N


Output

Print the maximum possible value of s.

Examples

Input

3
7 12 8


Output

4


Input

2
11 11


Output

2


Input

1
0


Output

0
#設定
import sys
input = sys.stdin.buffer.readline

from collections import defaultdict

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N = int(input())
	D = getlist()
	if N >= 24:
		print(0)
	elif N >= 12:
		d = defaultdict(int)
		judge = "Yes"
		for i in D:
			d[i] += 1
		if d[0] >= 1:
			judge = "No"
		if d[12] >= 2:
			judge = "No"
		for i in range(1, 12):
			if d[i] >= 3:
				judge = "No"
		if judge == "No":
			print(0)
		else:
			print(1)
	else:
		ans = 0
		for i in range(1 << N):
			L = [0, 24]
			for j in range(N):
				if ((i >> j) & 1) == 1:
					L.append(D[j])
				else:
					L.append(24 - D[j])
			L = sorted(L)
			val = 24
			for i in range(N + 1):
				val = min(val, L[i + 1] - L[i])
			ans = max(ans, val)
		print(ans)

if __name__ == '__main__':
	main()