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


def solve(n, ds):
    if n >= 24:
        return 0
    freq = Counter(ds)
    if (0 in freq) or (freq[12] >= 2) or max(freq.values()) >= 3:
        return 0
    up_low = [0, 0]
    switch = 0
    ans = 25
    for d, s in sorted(freq.items()):
        if s == 2:
            ans = min(ans, d - up_low[0], d - up_low[1])
            up_low[0] = up_low[1] = d
        else:
            ans = min(ans, d - up_low[switch])
            up_low[switch] = d
            switch ^= 1
    ans = min(ans, 24 - sum(up_low))
    return ans


print(solve(int(input()), list(map(int, input().split()))))
