#include<cstdio>
#include<queue>
#define N 100005
#define ll long long
using namespace std;
int n,a[N],b[N];ll ans;bool f;
struct node{int v,i;bool operator<(node y)const{return v<y.v;}};
priority_queue<node>q;
int read(){
    int sum=0;bool f=0;char c=getchar();
    for(;c<48||c>57;c=getchar())if(c==45)f=1;
    for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
    return f?-sum:sum;
}
int main(){
    freopen("nit.in","r",stdin);freopen("nit.out","w",stdout);
    n=read();
    for(int i=1;i<=n;i++)a[i]=read(),b[i]=read();
    for(int i=1;i<=n;i++)q.push({a[i]-b[i],i<<1});
    while(q.size())
    {
        node u=q.top();q.pop();
        if(u.i&1^1)q.push({0,u.i|1});
        if(f)if(u.i&1)ans-=b[u.i>>1];else ans-=a[u.i>>1];
        else if(u.i&1)ans+=b[u.i>>1];else ans+=a[u.i>>1];
        f=!f;
    }
    printf("%lld",ans);
    return 0;
}