#include<bits/stdc++.h>
using namespace std;
const int N=1e5+5;
int n,ansa,ansb;
struct node{
    long long a,b;
}f[N];
bool cmp(node x,node y){
    return x.a-x.b>y.a-y.b;
}
int main(){
    freopen("nit.in","r",stdin);
    freopen("nit.out","w",stdout);
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>f[i].a>>f[i].b;
    }
    sort(f+1,f+1+n,cmp);
    for(int i=1;i<=n;i++){
        if(i%2==1){
            ansa+=f[i].a;
        }else{
            ansb+=f[i].b;
        }
    }
    cout<<ansa-ansb<<"\n";
    return 0;
}