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
N = int(input())
D = list(map(int, input().split()))
rec = [0] * 13
for i in range(N):
    rec[D[i]] += 1

if rec[0] >= 1:
    print(0)
    exit()

ans = 0
for i in range(1 << 12):
    tmp = [0]
    for j in range(13):
        if rec[j] >= 3:
            print(0)
            exit()
        elif rec[j] == 2:
            tmp.append(j)
            tmp.append(24 - j)
        elif rec[j] == 1:
            if i & 1 << j:
                tmp.append(j)
            else:
                tmp.append(24 - j)
    tmp = sorted(tmp)
    pre = tmp[0]
    num = float("inf")
    for i in range(1, len(tmp)):
        num = min(num, tmp[i] - pre)
        pre = tmp[i]

    ans = max(min(num, 24 - tmp[-1]), ans)

print(ans)
