#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
typedef complex<ld> Point;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;

int n;
vector<int> d;


void solve(){
    cin >> n;
    d.resize(n,0);
    rep(i,n){
        cin >> d[i];
    }
    sort(d.begin(),d.end());
    vector<int> t(n+1,0);
    rep(i,n){
        if (i%2==0) t[i]=d[i];
        else t[i]=24-d[i];
    }

    ll ans=12;
    rep(i,n+1){
        rep(j,i){
            ans=min(ans,(ll)abs(t[i]-t[j]));
        }
    }

    cout << ans << endl;
    
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    solve();
}