#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = (1 << 30);
const ll INFL = (1LL << 62);
const ll MOD = 1000000007;
template <class T>
bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
T gcd(T a, T b) {
  return b ? gcd(b, a % b) : a;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
template <class T>
ll mod_pow(ll a, ll n, T mod) {
  mod = (ll)mod;
  ll res = 1, p = a % mod;
  while (n) {
    if (n & 1) res = res * p % mod;
    p = p * p % mod;
    n >>= 1;
  }
  return res;
}
template <int mod>
struct ModInt {
  using ll = long long;
  ll x;
  ModInt() : x(0) {}
  ModInt(int y) : x(y >= 0 ? ll(y % mod) : (ll)((mod - (-y) % mod))) {}
  ModInt(ll y) : x(y >= 0 ? y % mod : (mod - (-y) % mod)) {}
  ModInt &operator+=(const ModInt &rhs) {
    if ((x += rhs.x) >= mod) x -= mod;
    return *this;
  }
  ModInt &operator-=(const ModInt &rhs) {
    if ((x += mod - rhs.x) >= mod) x -= mod;
    return *this;
  }
  ModInt &operator*=(const ModInt &rhs) {
    x = x * rhs.x % mod;
    return *this;
  }
  ModInt &operator/=(const ModInt &rhs) {
    *this *= rhs.inverse();
    return *this;
  }
  ModInt operator-() const { return ModInt(-x); }
  ModInt operator+(const ModInt &rhs) const { return ModInt(*this) += rhs; }
  ModInt operator-(const ModInt &rhs) const { return ModInt(*this) -= rhs; }
  ModInt operator*(const ModInt &rhs) const { return ModInt(*this) *= rhs; }
  ModInt operator/(const ModInt &rhs) const { return ModInt(*this) /= rhs; }
  ModInt operator==(const ModInt &rhs) const { return x == rhs.x; }
  ModInt operator!=(const ModInt &rhs) const { return x != rhs.x; }
  friend ostream &operator<<(ostream &os, const ModInt &rhs) {
    return os << rhs.x;
  }
  friend istream &operator>>(istream &is, ModInt &rhs) {
    ll t;
    is >> t;
    rhs = ModInt<mod>(t);
    return (is);
  }

 private:
  ModInt inverse() const {
    ll a = x, u = 1LL, v = 0LL, t, b = (ll)mod;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }
};
using mint = ModInt<MOD>;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> D(N + 1, 0);
  for (int i = 0; i < (int)(N); i++) cin >> D[i];
  int ans = INF;
  for (int i = 0; i < (int)(N + 1); i++)
    for (int j = i + 1; j < N + 1; ++j) {
      int tmp = 0;
      tmp = max(tmp, abs(D[i] - D[j]));
      tmp = max(tmp, abs((24 - D[i]) - D[j]));
      tmp = max(tmp, abs((24 - D[i]) - (24 - D[j])));
      tmp = max(tmp, abs(D[i] - (24 - D[j])));
      ans = min(ans, tmp);
    }
  cout << (ans > 12 ? 24 - ans : ans) << endl;
  return 0;
}
