#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    ll n;
    cin >> n;
    cin.ignore();
    vector<string> s(n);
    getline(cin, s[0]);
    if (s[0].find(" ") != string::npos) {
        cout << "\"assert\"" << endl;
        return 0;
    }
    rep(i, 2) cin >> s[i + 1];
    vector<ll> a(n);
    rep(i, n) a[i] = atoi(s[i].c_str());
    set<ll> sum;
    rep(i, n) {
        reps(ii, i + 1, n) {
            sum.insert(a[i] + a[ii]);
        }
    }
    auto it = sum.end();
    it--; it--;
    cout << *it << endl;
    return 0;
}