Score : $500$ points

Problem Statement

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 $s$.

3
7 12 8

4

For example, consider the situation where it is $7$, $12$ and $16$ o'clock in each person's city at the moment when it is $0$ o'clock in Takahashi's city. In this case, the time gap between the second and third persons' cities is $4$ hours.

2
11 11

2

1
0

0

Note that Takahashi himself is also a participant.