#include <algorithm>
#include <bitset>
#include <cctype>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <ctime>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

const int INF = 0x3f3f3f3f;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
/*----------------------------------------*/

int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  // freopen("input.txt", "r", stdin);

  int n; cin >> n;
  vector<int> jikoku{0, 24}, d(n);
  REP(i, n) {
    cin >> d[i];
    if (d[i] == 0) {
      cout << 0 << '\n';
      return 0;
    }
  }
  sort(ALL(d));
  REP(i, n) {
    int index1 = distance(jikoku.begin(), lower_bound(ALL(jikoku), d[i])), index2 = distance(jikoku.begin(), lower_bound(ALL(jikoku), 24-d[i]));
    int sa1 = min(jikoku[index1]-d[i], d[i]-jikoku[index1-1]), sa2 = min(jikoku[index2]-(24-d[i]), (24-d[i])-jikoku[index2-1]);
    if (sa1 >= sa2) jikoku.push_back(d[i]);
    else jikoku.push_back(24-d[i]);
    sort(ALL(jikoku));
  }
  int ans = 12;
  REP(i, jikoku.size()-1) ans = min(ans, jikoku[i+1]-jikoku[i]);
  cout << ans << '\n';
  return 0;
}
