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 = [int(d) for d in input().split()]
Dcount = [0] * 13

for i in range(13):
    Dcount[i] = D.count(i)
if Dcount[0] > 0 or Dcount[12] > 1: print(0)
else:
    for i in Dcount[1:12]:
        if i >= 3:
            print(0)
            break
    else:
        base = [0, 24]
        if Dcount[12] == 1: base.append(12)
        Single = []
        for i in range(1, 12):
            if Dcount[i] == 2:
                base.append(i)
                base.append(24-i)
            elif Dcount[i] == 1:
                Single.append(i)
        lensingle = len(Single)
        minmax = 0
        for i in range(2**lensingle):
            Clock = base.copy()
            bit = format(i, "b").zfill(lensingle)
            for j in range(lensingle):
                if bit[j] == "0": Clock.append(Single[j])
                else: Clock.append(24 - Single[j])
            Clock.sort()
            minsub = 24
            for j in range(1, len(Clock)):
                minsub = min(minsub, Clock[j] - Clock[j-1])
            minmax = max(minmax, minsub)
        print(minmax)