include<bits/stdc++.h>

using namespace std; int main(){ long long n,s,a,cvb=0; cin>>n; vector<long long > v; for(int i=0;i<2*n;i++){ cin>>s>>a; cvb+=s;

   v.push_back(a-s);

} sort(v.rbegin(), v.rend()); for(int i=0;i<n;i++){ cvb+=v[i]; } cout<<cvb;

}

include <bits/stdc++.h>

using namespace std;

int main () {

long long n, seher, axsam, cem = 0;

cin >> n;

vector < int >v;

for (int i = 0; i < 2 * n; i++) {

cin >> seher >> axsam;

cem = cem + seher;

v.push_back (axsam - seher);

} sort (v.begin (), v.end ());

reverse (v.begin (), v.end ());

for (int i = 0; i < n; i++) {

cem = cem + v[i];

} cout << cem << endl;

}

/* 3 6 cem = 3 v = 3 7 1 cem = 7 v = -6 4 9 cem = 4 v= 5 10 11 cem = 10 v = 1

cem = 3 + 7 + 4 + 10 + 5 + 3 */