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~ .

Sample Input 1

3
7 12 8

Sample Output 1

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.

Sample Input 2

2
11 11

Sample Output 2

2

Sample Input 3

1
0

Sample Output 3

0

Note that Takahashi himself is also a participant.