#include <bits/stdc++.h>
#define LL long long

using namespace std;

LL a[100005];

void solve()
{
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    sort(a + 1, a + n + 1);

    cout << max({ (LL)0, a[n], a[n] + a[n - 1] }) << "\n";
}

int main()
{
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    int tt = 1;
    //cin >> tt;
    while (tt--)
        solve();
}