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

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {
    int n;
    int[] ds;
    int[] cnts = new int[13];
    boolean[] ts = new boolean[24];
    int ans = -1;
    public static void main(String[] args) {
        Main m = new Main();
        m.read();
        m.solve();
    }

    private void read() {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        ds = new int[n];
        cnts[0]++;
        for (int i = 0 ; i < n; i++) {
            ds[i] = sc.nextInt();
            cnts[ds[i]]++;
        }
    }

    private void solve() {
        ts[0] = true;
        int mx = Arrays.stream(cnts).max().getAsInt();
        if (mx >= 3 || cnts[0] >= 2) {
            System.out.println(0);
            return;
        }
        ArrayList<Integer> ls = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            if (cnts[ds[i]] == 2) {
                ts[ds[i] % 24] = true;
                ts[(24 - ds[i]) % 24] = true;
            }
            else {
                ls.add(ds[i]);
            }
        }
        int[] as = new int[ls.size()];
        for (int i = 0; i < as.length; i++)
            as[i] = ls.get(i);
        dfs(0, as);
        System.out.println(ans);

    }

    private void dfs(int i, int[] as) {
        if (i == as.length) {
            calc();
            return;
        }
        ts[as[i] % 24] = true;
        dfs(i+1, as);
        ts[as[i] % 24] = false;
        ts[(24 - as[i]) % 24] = true;
        dfs(i+1, as);
        ts[(24 - as[i]) % 24] = false;
    }

    private void calc() {
        int mn = 13;
        int old = 0;
        for (int i = 1; i < ts.length; i++) {
            if (!ts[i])
                continue;
            mn = Math.min(mn, i - old);
            old = i;
        }
        mn = Math.min(mn, 24 - old);
        ans = Math.max(ans, mn);
    }
}
