#include <iostream> 
#include <queue>
#include <utility>
using namespace std;
typedef pair<int,int> pii;
const int N=1e5+5;
int a[N],b[N];
priority_queue<pii>p;
priority_queue<int>bs;
int main(){
    freopen("nit.in","r",stdin);
    freopen("nit.out","w",stdout);
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i]>>b[i];
        p.push(make_pair(a[i],b[i]));
    }
    long long ansa=0,ansb=0;
    for(int i=1;i<=2*n;i++){
        if(bs.empty()||p.top().first>bs.top()){
            pii now=p.top();
            if(i&1){
                ansa+=now.first;
            }else{
                ansb+=now.first;
            }
            bs.push(now.second);
            p.pop();
        }else{
            int now=bs.top();
            if(i&1){
                ansa+=now;
            }else{
                ansb+=now;
            }
            bs.pop();
        }
    }
    cout<<ansa-ansb;
    return 0;
}