#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N=1e5+10;
int a[N],b[N],tot,sum,ans;
struct node{
    int sum,num; 
}c[N];
bool cmp(node a1,node b1){
    return a1.sum>b1.sum;
} 
signed 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];
        c[i].sum=a[i]+b[i];
        c[i].num=i;
        tot+=a[i]+b[i];
    }
    sort(c+1,c+1+n,cmp);
    int suma=0,sumb=0;
    for(int i=1;i<=n;i++){
        if(i%2==1){
            suma+=a[c[i].num];
        }else
             sumb+=b[c[i].num];
    }
    ans=suma*2-tot;
    cout<<suma-sumb<<endl;
    return 0;
}