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
from collections import Counter, defaultdict
import sys
sys.setrecursionlimit(10 ** 5 + 10)
# input = sys.stdin.readline
from math import factorial
import heapq, bisect
import math
import itertools


import queue
from collections import deque


def main():
    num = int(input())
    data = list(map(int, input().split()))
    count = Counter(data)

    ans = 0
    for i in range(2 ** 11):
        bin_list = bin(i)[2:]
        bin_list = bin_list.zfill(11)
        bin_list = list(map(int, list(bin_list)))
        now_data = [0, 24]

        if count[12] >= 2:
            print(0)
            sys.exit()
        elif count[12] == 1:
            now_data.append(12)

        if count[0] >= 1:
            print(0)
            sys.exit()


        for j in range(1, 12):
            if count[j] == 0:
                continue
            elif count[j] >= 3:
                print(0)
                sys.exit()
            elif count[j] == 2:
                now_data.append(j)
                now_data.append(24 - j)
            elif bin_list[j - 1]:
                now_data.append(j)
            else:
                now_data.append(24 - j)
        now_data.sort()

        kari = 12
        # print(now_data)
        for j in range(len(now_data) - 1):
            kari = min(kari, now_data[j + 1] - now_data[j])
        ans = max(ans, kari)

    print(ans)




if __name__ == '__main__':
    main()
    # test()

