#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;
    }
  }

  i64 a[4];
  a[0] = stoi(s);

  vector<i64> vec;
  cin >> a[1] >> a[2];

  i64 case1 = a[0] + a[1];
  i64 case2 = a[1] + a[2];
  i64 case3 = a[0] + a[2];

  vec.push_back(case1);
  vec.push_back(case2);
  vec.push_back(case3);

  sort(all(vec), greater<i64>());

  cout << (vec[0] == vec[1] ? vec[2] : vec[1]) << "\n";

  return 0;
}