acmnb

//#include<bits/stdc++.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<array>

#define long long long
#define nln '\n'

const long N = 4*1e5 + 10;

using namespace std;

// GLobal variables: n

long n;
vector<long> a, b;
priority_queue<array<long, 3>, vector<array<long,3>>, less<array<long, 3>>> pqu;
vector<pair<long, long>> pic;

void pick()
{
    long n1 = n/2, n2 = n/2;

    while (!pqu.empty())
    {
        auto tak = pqu.top();
        pqu.pop();

        if (n1 == 0)
        {
            pic.push_back({tak[1], 2});
            continue;
        }
        if (n2 == 0)
        {
            pic.push_back({tak[1], 1});
            continue;
        }

        if (tak[2] == 1)
        {
            --n1;
            pic.push_back({tak[1], tak[2]});
            continue;
        }

        if (tak[2] == 2)
        {
            --n2;
            pic.push_back({tak[1], tak[2]});
        }
    }
}

void code()
{
    long ans = 0;
    for (const auto &i : pic)
        //cout << i.first << ": " << i.second << nln;
        if (i.second == 1)
            ans += a[i.first];
        else
            ans += b[i.first];
    cout << ans << nln;
}

void data()
{
    cin >> n;
    n *= 2;
    a.resize(n+1, 0);
    b.resize(n+1, 0);
    for (long i = 1; i <= n; ++i)
    {
        cin >> a[i] >> b[i];
        long per = -1;
        if (a[i] <= b[i])
            per = 1;
        else
            per = 2;
        pqu.push({abs(a[i]-b[i]), i, per});
    }
}

void process()
{
    pick();
    code();
}

int main()
{
    data();
    process();
    return 0;
}