#include <bits/stdc++.h>
using namespace std;
int main(void){
    int N; cin >> N;
    cin.ignore();
    vector<long long> a(N);
    for (int i = 0; i < N; i++) {
        if (i == 0) {
            string s;
            getline(cin, s);
            for (int j = 0; j < s.length(); j++) {
                if (s[j] == ' ') {
                    cout << "\"assert\"" << endl;
                    return 0;
                }
            }
            a[0] = stoll(s);
        } else {
            cin >> a[i];
        }
    }
    vector<long long> ans;
    for (int i = 0; i < N; i++) {
        for (int j = i+1; j < N; j++) {
            ans.push_back(a[i] + a[j]);
        }
    }
    sort(ans.begin(), ans.end(), greater<long long>());
    ans.erase(unique(ans.begin(), ans.end()), ans.end());
    cout << ans[1] << endl;
}