ROTATION

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

constexpr int N = 4e5 + 5;
constexpr ll Inf = 1e17;

int n, a[N];

void Read()
{
    cin >> n;

    for (int i = 1; i <= n * 2; ++i)
        cin >> a[i];
}

void Solve()
{
    if (n == 1)
        cout << a[1];
    else if (n == 2)
        cout << max(max(a[1] + a[2], a[2] + a[4]), max(a[3] + a[4], a[3] + a[1]));
    else
    {
        sort(a + 1, a + n * 2 + 1, greater<int>());
        ll ans(0);

        for (int i = 1; i <= n; ++i)
            ans += a[i];

        cout << ans;
    }
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    Read();
    Solve();
}