#include <bits/stdc++.h>                                                                      
                                                                                              
using namespace std;                                                                          
                                                                                              
#define all(x) x.begin(), x.end()                                                             
#define rep(i, n) for (int i = 0; i < n; ++i)                                                 
#define reps(i, m, n) for (int i = m; i <= n; ++i)                                            
                                                                                              
using i64 = long long;                                                                        
using pii = pair<i64, i64>;                                                                   
                                                                                              
template<class A, class B>inline bool chmax(A &a, const B &b){return b > a ? a = b,1 : 0;}    
template<class A, class B>inline bool chmin(A &a, const B &b){return b < a ? a = b,1 : 0;}    
                                                                                              
constexpr int INF = 0x3f3f3f3f;                                                               
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;                                                    
constexpr int mod = int(1e9) + 7;                                                             
                                                                                              
signed main()                                                                                 
{                                                                                             
  ios::sync_with_stdio(false);                                                                
  cin.tie(nullptr);                                                                           
  int N;                                                                                      
  cin >> N;                                                                                   
  cin.ignore();                                                                               
  string s;                                                                                   
  getline(cin, s);                                                                            
  for (auto e : s) {                                                                          
    if (e == ' ') {                                                                           
      cout << '"' <<  "assert" << '"' << "\n";                                                
      return 0;                                                                               
    }                                                                                         
  }                                                                                           
                                                                                              
  s.clear();                                                                                  
                                                                                              
  vector<int> vec;                                                                            
  i64 a[4];                                                                                   
  rep(i, N) {                                                                                 
    cin >> a[i];                                                                              
  }                                                                                           
  int case1 = a[0] + a[1];                                                                    
  int case2 = a[1] + a[2];                                                                    
  int case3 = a[0] + a[2];                                                                    
                                                                                              
  vec.push_back(case1);                                                                       
  vec.push_back(case2);                                                                       
  vec.push_back(case3);                                                                       
                                                                                              
  sort(all(vec), greater<int>());                                                             
                                                                                              
  cout << (vec[0] == vec[1] ? vec[2] : vec[1]) << "\n";                                       
  return 0;                                                                                   
}