#include <bits/stdc++.h>

using namespace std;

int main() {
    //cin读入优化
    std::ios::sync_with_stdio(false);
    //输入+输出重定向
    freopen("../number.in", "r", stdin);
    freopen("../number.out", "w", stdout);

    int n;
    cin >> n;
    vector<int> a(n + 1, 0);
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    sort(a.begin() + 1, a.end());
    //两两对比，找最大值
    int maxx = -1;
    for (int i = 1; i <= n / 2; i++) {
        if (a[i] + a[n - i + 1] > maxx) maxx = a[i] + a[n - i + 1];
    }
    cout << maxx << endl;
    //关闭文件
    fclose(stdin);
    fclose(stdout);
    return 0;
}