#include <iostream>
#include <bitset>
#include <map>
#include <vector>
#include <set>
#include <queue>
#define ll long long
using namespace std;
int main()
{
	int n,x,y;
	ll sum1=0,sum2=0;
	cin >> n;
	multiset<pair<int, int>, greater<pair<int, int>>> p, c, a, b;
	for (int i = 0; i < n; i++)
	{
		cin >> x >> y;
		p.insert({x, -y});
		c.insert({y, -x});
	}
	a=p,b=c;
	for (int i = 0; i < n / 2; i++)
	{
		if (sum1 > sum2)
		{
			auto q = *c.begin();
			sum2 += q.first;
			c.erase(c.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			p.erase(p.find(q));
			q = *p.begin();
			sum1 += q.first;
			p.erase(p.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			c.erase(c.find(q));
		}
		else
		{
			auto q = *p.begin();
			sum1 += q.first;
			p.erase(p.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			c.erase(c.find(q));
			q = *c.begin();
			sum2 += q.first;
			c.erase(c.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			p.erase(p.find(q));
		}
	}
	p=a,c=b;
	ll mx1=sum1,mx2=sum2;
	sum1=0,sum2=0;
	for (int i = 0; i < n / 2; i++)
	{
		if (sum1 >= sum2)
		{
			auto q = *c.begin();
			sum2 += q.first;
			c.erase(c.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			p.erase(p.find(q));
			q = *p.begin();
			sum1 += q.first;
			p.erase(p.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			c.erase(c.find(q));
		}
		else
		{
			auto q = *p.begin();
			sum1 += q.first;
			p.erase(p.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			c.erase(c.find(q));
			q = *c.begin();
			sum2 += q.first;
			c.erase(c.begin());
			swap(q.first, q.second);
			q.first *= -1, q.second *= -1;
			p.erase(p.find(q));
		}
	}
	cout<<max(mx1+mx2,sum1+sum2);
}