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 = sorted(list(map(int, input().split())))

D1 = [0] + [(D[i] if i % 2 == 0 else 24 - D[i]) for i in range(N)]
D2 = [0] + [(D[i] if i % 2 == 0 else 24 - D[i]) for i in range(N)]

ans1 = float('inf')
ans2 = float('inf')

for i in range(N + 1):
    for j in range(i + 1, N + 1):
        ans1 = min(ans1, abs(D1[i] - D1[j]))
        ans2 = min(ans2, abs(D2[i] - D2[j]))

print(max(ans1, ans2))
