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
#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <utility>
#define rep(i,n) for(int i=0;i<n;++i)
#define rep1(i,n) for(int i=1;i<=n;++i)
using namespace std;
int main()
{
  int n;
  cin >> n;
  vector<int> d(n);
  rep(i,n){
    cin >> d[i];
    if(d[i] == 0){
      cout << 0 << "\n";
      return 0;
    }
  }

  map<int,int> mp;
  rep(i,n) mp[d[i]]++;
  vector<int> des(0),tem(0);
  
  for(auto& itr:mp){
    if(itr.second>=3){
      cout << 0 << "\n";
      return 0;
    }
    else if(itr.second==2){
      des.push_back(itr.first);
      des.push_back(24-itr.first);
    }
    else{
      tem.push_back(itr.first);
    }
  }

  int m = tem.size();
  int maxs = 0;
  rep(S,(1<<m)){
    vector<int> vec = des;
    vec.push_back(0);
    rep(i,m){
      if((S>>i)&1){
	vec.push_back(24-tem[i]);
      }
      else{
	vec.push_back(tem[i]);
      }
    }

    int mins = 50;
    int vs = vec.size();
    rep(i,vs) rep(j,vs){
      if(i==j) continue;
      int a = vec[i],b = vec[j];
      if(a>b) swap(a,b);
      mins = min(mins , min(b-a , 24+a-b));
    }
    maxs = max(maxs,mins);
  }
  
  cout << maxs << "\n";
  return 0;
}
