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
import itertools


def calc(s):
    ret = 24
    for i in range(1, len(s)):
        ret = min(ret, s[i] - s[i-1])
    return ret


def main():
    N = int(input())
    D = list(map(int, input().split()))
    if D.count(0) >= 1 or D.count(12) >= 2:
        print(0)
        return
    cnt = [0] * 13
    for d in D:
        cnt[d] += 1
    fixed = [0, 24]
    variable = []
    for i in range(1, 12):
        if cnt[i] >= 3:
            print(0)
            return
        elif cnt[i] == 2:
            fixed.append(i)
            fixed.append(24-i)
        elif cnt[i] == 1:
            variable.append(i)
    if cnt[12] == 1:
        fixed.append(12)
    ans = 0
    for p in itertools.product((False, True), repeat=len(variable)):
        s = list(fixed)
        for i in range(len(variable)):
            if p[i]:
                s.append(variable[i])
            else:
                s.append(24-variable[i])
        s.sort()
        ans = max(ans, calc(s))
    print(ans)


if __name__ == "__main__":
    main()
