#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(){
  int n;cin>>n;
  vector<int> a;
  a.push_back(0);
  for(int i = 0; n > i; i++){
    int tmp;cin>>tmp;
    a.push_back(tmp);
  }
  sort(a.begin(),a.end());
  for(int i = 0; n >= i; i+=2){
    a[i] = (24 - a[i])%24;
  }
  sort(a.begin(),a.end());
  int ans = 10000;
  for(int i = 1; n >= i; i++){
    ans = min(ans,a[i]-a[i-1]);
  }
  cout << ans << endl;
}