#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define foru(a,b,c) for(ll a=b;a<=c;a++)

ll n,a[100005],b[100005],ans;
short chose[100005];

int main(){
    freopen("nit.in","r",stdin);
    freopen("nit.out","w",stdout);
    cin>>n;
    foru(i,1,n){
        cin>>a[i]>>b[i];
    }
    ll va=0,vb=0;
    foru(depth,1,(n<<1)){
        ll ma=0,mai;
        foru(i,1,n){
            if(((chose[i]&1)==(depth&1))&&chose[i]!=0){
                continue;
            }
            if(chose[i]!=0&&chose[i]!=3){
                if(b[i]>ma){
                    ma=b[i],mai=i;
                }
            }else if(chose[i]==0){
                if(a[i]>ma){
                    ma=a[i],mai=i;
                }
            }
        }
        if(depth&1){
            va+=ma;
            if(chose[mai])chose[mai]=3;
            else chose[mai]=1;
        }else{
            vb+=ma;
            if(chose[mai])chose[mai]=3;
            else chose[mai]=2;
        }
//        cerr<<"#1 "<<depth<<" "<<mai<<" "<<chose[mai]<<" "<<ma<<endl;
//        cerr<<"#2 "<<va<<" "<<vb<<endl;
    }
    cout<<va-vb;
    return 0;
}