WORKSHOP

include <bits/stdc++.h>

using namespace std;

int main() { int n,a,b; cin >> n; vector<int> chenh(2*n); long long t=0;

for (int i=0;i<2*n;i++) {
    cin>>a>>b;
    t+=b;
    chenh[i]=a-b;
}

sort(chenh.begin(), chenh.end());

for (int i=0;i<n;i++) {
    t+=chenh[i];
}
cout << t;
return 0;

}